This is part of the series on representing disability in D&D.
In my previous post in the series I looked at lower-limb prosthetics. I’m now starting a new campaign, and one of my players has been inspired by my posts to play a character with a disability, but rather than working with the lower-limb impairment I have already worked up mechanics for, he has decided to play someone who was born with only one arm.
So, necessity being the mother of invention, it’s time to work out mechanics for upper-limb impairments.
Principles
What I said in the previous post is worth restating. In developing these mechanics, I am trying to remember this statement from The Combat Wheelchair:
Remember: The Combat Wheelchair does not give a disabled character any kind of ‘advantage’ over the able-bodied characters in their party. It merely enables a disabled character to continue adventuring. You should not be punished for something you can’t help. To be punished for having a disability is cruel.
Anyone can be a hero.
I am trying to work to the following guiding principles in my development:
- The prosthetics allow disabled adventurers to participate fully in adventures
- The rules should be simple enough to use at a table without constant referring back to the ruleset
- More advanced/expensive prosthetics are available which are more durable and/or provide more advanced features
- These advanced features may be beyond what a normal adventurer can do in some respect, however even advanced prosthetics still have downsides, and the more benefit they give, the more likely they are to be specialised for that benefit and impaired for general use
- Putting on, taking off, changing or adjusting prosthetics takes time
There certain drawbacks to disability which are gritty but not necessarily heroic or interesting and may bog down the game, so these will be deferred to optional additional rules.
Missing arm or hand
So what does it mean to be missing an arm?
Missing arm or hand – the official line
Let’s start with the official rules:
Lose an Arm or a Hand. You can no longer hold anything with two hands, and you can hold only a single object at a time. Magic such as the regenerate spell can restore the lost appendage.
Hmm. There are two things which jump out at me here.
First, there is a big difference between losing an arm and losing a hand. If you are missing only part of the arm, the stump is definitely still useful for gripping, even if it’s not as dexterous as a full hand. Just watch Gill on this year’s Great British Sewing Bee for an example.
On the other hand, missing part of an arm will affect more than just holding things. And missing most or all of the arm will affect more than if there is a useful stump which can be used for gripping. It will also affect what prosthetics can be available.
Missing a whole arm
Since the character in my campaign was born with only one arm, I will initially focus on mechanics for a whole lost arm.
Think about what you use two hands for. Now think about what would be affected if you only have one arm.

Obviously you won’t be able to dual-wield, or hold anything which requires two hands. You won’t be able to use both a weapon and a shield. You won’t be able to hold something in one hand while you manipulate or do something with the other hand, so you may need to make more use of surfaces to place things on temporarily.
Certain gross motor skills will also be affected. This will definitely affect climbing and swimming, and possibly also things like catching.
On the other hand (oops!) there is plenty that won’t be affected. It shouldn’t affect normal movement or jumping. It won’t affect fine motor skills as long as the task can be reasonably achieved using only one hand, or with some sort of wedging to hold the item in place of holding it with the other hand, so most Sleight of Hand checks are likely to be unaffected.
What isn’t affected
There are things which could conceivably be affected, but which I will assume that a character would be able to adjust so that they can achieve them without noticeable impairment. For example:
- Try standing on one foot, up on your toes. Notice how you use your arms to help you balance? (If not, I’m impressed with your natural balance 😊). Balance could easily be affected by having only one arm. However, I would assume that the character would get used to living without an arm and would make adjustments so that there is no need to introduce any mechanical changes to balance.
- Spellcasting could go either way – it could be argued that spells with a somatic component need exact replication of movements which might not be possible without both arms. However, I don’t see any point in taking this line. I would suggest allowing normal spellcasting. I assume that the character and their teacher can work out effective alternatives to any movements which would normally require both arms.
Obviously anything which requires two arms is out, and it’s up to the GM to decide when that applies, but realistically I would think that is less frequent than you might think at first. Assume the character is inventive with workarounds, and be very open to the player arguing ways they work around the lack of an arm.
Weapons and armour
The weapons table helpfully lists which weapons are two-handed: greatclub, glaive, greataxe, greatsword, halberd, maul, pike, light and heavy crossbows (hand crossbow is single-handed), shortbow and longbow.
I would have thought that the various polearms (glaive, halberd, pike) could be adjusted or have special variants which can be used one-handed – maybe more expensive and/or with a penalty.

Similarly, since the propulsive force of a crossbow comes from the inbuilt mechanism, I see no reason why they couldn’t be adapted for use with a single arm. In this case, I would think they would be specialised weapons which cost more, but probably not with much penalty to the attack. Reloading would be harder with one hand, though. Maybe it takes a round to load for a light crossbow and two for a heavy one, and maybe a one-handed heavy crossbow requires a certain degree of strength to wield.
Missing part of an arm
If you have a stump, however long, you are clearly in a better position than if you are missing the complete arm, and this will probably be better if you have still have the elbow. The stump can be used for bracing and holding in so many ways, and can also take a prosthetic to further improve grip. Climbing, swimming and catching will be less affected, and if you have enough arm you can wear a shield – probably you need at least part of the lower arm, although maybe it would be possible to get specially adapted shields which only strap to the upper arm and only give +1 bonus to AC instead of +2.
You will probably need some sort of prosthetic or adaptation to be able to use a 2-handed weapon, and there may still be some penalty, and obviously the stump doesn’t have the fine motor skills necessary for the typical things which would result in Sleight of Hand checks (though if you are only missing one hand, you can use the one which exists for those).
However, having read Jamie Andrew’s “Life and Limb” and watched Gill on the Sewing Bee, it is clear that stumps can do a lot, and even with no hands it is possible to live an active life. It seems in many cases that simple solutions are the best – rather than fancy prosthetic arms which look like real arms and hands, Jamie uses cutlery slipped into a rubber band around his stump for eating, and a simple claw gripper which can be opened and closed using a strap around his opposite shoulder for finer control.
Mechanics
So, let’s put some crunch on this. I need explicit mechanics my player can use.
Missing arm
This is the most extreme case for a single arm, but assumes the character has a fully working arm.
- Climbing Strength (Athletics) checks have a -5 penalty
- Swimming Strength (Athletics) checks have a -3 penalty
- Dexterity (Sleight of Hand) checks which need both hands (e.g. catching) have a -3 penalty
- Cannot carry anything which requires two hands (such as a tray)
- Cannot dual-wield
- Cannot wear a shield and wield a weapon simultaneously
- Cannot use an unmodified 2-handed weapon
- A modified light crossbow costs 40gp from a specialist blacksmith, requires proficiency, and requires a full turn to reload
- A modified glaive or halberd costs 40gp from a specialist blacksmith, requires proficiency, and has a -2 penalty to attack and damage rolls
Missing part of one arm above elbow
This is less severe than the whole arm missing since they have a stump they can make use of, but the stump is fairly short and doesn’t include the elbow. Again this assumes the character’s other arm is fully working.
- Climbing Strength (Athletics) checks have a -3 penalty
- Swimming Strength (Athletics) checks have a -2 penalty
- Dexterity (Sleight of Hand) checks which need both hands (e.g. catching) have a -2 penalty
- Carrying anything which requires two hands (such as a tray) requires a situational Dexterity (Sleight of Hand) check to avoid dropping. The DC should be set based on the weight and awkwardness of the item being carried; e.g. a tray with drinks DC13, a large chest with handles DC15
- Cannot dual-wield
- Cannot wear a normal shield and wield a weapon simultaneously
- An upper-arm shield costs 25gp from a specialist armourer and gives a +1 to AC
- Cannot use an unmodified 2-handed weapon
- A modified light crossbow costs 40gp from a specialist blacksmith, requires proficiency, and requires a full turn to reload
- A modified glaive or halberd costs 40gp from a specialist blacksmith, requires proficiency, and has a -2 penalty to attack and damage rolls
Missing part of one arm below elbow
This character still has most of their arm, including the elbow, which allows things to be gripped in the crook of the arm or balanced on the forearm. Again this assumes the character’s other arm is fully working.
- Climbing Strength (Athletics) checks have a -2 penalty
- Swimming Strength (Athletics) checks have a -1 penalty
- Dexterity (Sleight of Hand) checks which need both hands (e.g. catching) have a -1 penalty
- Carrying items which require two hands is normally fine unless there is a specific reason why a hand would make a difference
- Can dual-wield, but can only wield a specially modified weapon with the stump
- An upper-arm shield costs 25gp from a specialist armourer and gives a +1 to AC
- Can use a normal shield with modifications which cost 10gp from a blacksmith or specialist armourer
- Can use an unmodified crossbow
- Can use an unmodified polearm (glaive, halberd or pike) with a -1 penalty to attack rolls
- Cannot use any other unmodified 2-handed melee weapon or bow
Missing part of both arms
For simplicity, I have decided not to distinguish between above-elbow and below-elbow in this case. The key thing is that both arms end in stumps so no fine motor control is possible without some sort of assistance.
- Climbing Strength (Athletics) checks have a -3 penalty
- Swimming Strength (Athletics) checks have a -3 penalty
- Cannot use unmodified weapons
- Dexterity (Sleight of Hand) checks have a -10 penalty and require the use of both stumps
- Use of modified weapons/shields depends on the amount of arm, as per the single-arm versions above
Notes
As I said in the previous post, I have tried to think through appropriate impacts and effects with and without prosthetics based on descriptions in the references and application of physics/engineering, but I don’t have personal experience or know anyone who does. So I would welcome people trying these mechanics out, particularly those who know what it is like living missing part or all of an arm, and giving feedback. You can get in touch in replies to this post, by Twitter to @Melestrua, or email to Melestrua@melestrua.net
References
Key reading which has informed this:
- Jamie Andrew’s “Life and Limb” (as mentioned above). Jamie lost part of both arms and legs to frostbite in a storm when mountain climbing.
- Artificial Parts, Practical Lives, Modern Histories of Prosthetics. A collection of essays examining different aspects of prosthetics through history.
- The Body Factory. A graphic novel where a guy who has part of his arm amputated after a motorbike accident is taken through the history and future of prosthetics by Ambrose Paré, the French barber-surgeon who revolutionised the art of amputation.