So our Warforged just had his leg blasted off in a pretty gruesome attack. He wants to jam a sword in there as a makeshift peg leg.
We're using the online compendium as our official rule book and it doesn't have anything about how attachments/embedding works. Can any Warforged at all do it or does he need a perk/ability? I read about the ability in the Eberron-specific guide, but the compendium doesn't say anything about it. Can Warforged do it in just plain 4e?
Since the game rules do not include any way for you to lose limbs, they also do not include any solutions to lost limbs. If you houserule in limb loss, which I strongly recommend against, you also have to houserule any solutions. There was a similar situation in 3.5; this question and answer may therefore be useful to you.
Note that the discussion in that link of the game’s tone and premise is even stronger in 4e than it was in 3.5; 4e is even less interested in modeling these kinds of injuries than 3.5 was. Limb loss houserules cause even larger problems and represent an even larger departure from the game’s expectations. Even more than in 3.5, this sort of thing (the possibility, the consequences, and the potential remedies) should have been discussed before the game ever started.
Warforged components, that is, items that can be attached to or embedded in a warforged, do exist. These items are usually specifically designed for the purpose, but weapons (such as this sword) are an exception, per Eberron Player’s Guide page 114:
Weapons can be embedded or attached components. Two-handed weapons cannot be attached or embedded. A one-handed ranged or melee weapon can be attached to a hand, although you can still have only one weapon per hand, regardless of whether the weapon is held normally or attached. An attached weapon occupies your hand, and you must remove it to free the hand. A one-handed weapon that has the off-hand or light thrown property can be embedded.
But this is attaching the weapon to a hand, to be used as a weapon. Not attaching a sword to a leg-stump and attempting to walk on it. Since, per the above, there is no way to end up with a leg stump in the first place, the rules do not cover that, nor do they address the idea of “improvised components.” So while the rules do describe some body modification done by warforged, they fall far short of describing any process that would enable a warforged to do what this one would like to do. That must be a houserule.
For what it’s worth, the warforged are definitely described as tough enough to manage this process. Body modification is a common part of post-war warforged culture, and is a painless process for them. Reforged1 even go so far as to completely swap out most of their body parts for a more “organic” ones. Furthermore, seeing as limb-loss is, at least in my opinion, a really poor addition to 4e, I would personally be very quick to allow any convenient solution to eliminate the problem.
Realistically, it doesn’t make a lot of sense that a sword peg-leg would be just as good as his existing leg, but I probably would make it such anyway for the good of the game. I strongly recommend against permanent or significant penalties. Extremely temporary, rather minor penalties could be acceptable, particularly if this is the end of a dramatic arc and the warforged will be able to visit a proper repair shop soon.
Warforged have a set of rules for "components" which are attachments or embedded devices that are added on to their body. A component is a magic or mundane item that a Warforged character can either attach to an existing body part or embed within their body. The rules only provide information on how to make magic components, but they do imply that mundane items can be used as components ("A component doesn't take up the magic item slot of the same type, unless it is a magic item that goes in that slot"). Any Warforged can use a component, and an attachment is simply a standard action to put on or take off.
However, you cannot simply replace a Warforged leg with a sword and call it an attachment. The item has to be specially made as a component to suit that purpose, such as how an Armblade or any other Warforged component is made. Simply plugging the sword into the stub leg wouldn't necessarily hold it in place. The sword would be harder to balance on than a normal leg due to the difference in size, though special construction could mitigate that factor. Additionally, standing and walking on a sword-leg would probably ruin it as a weapon, dulling down the edge. It shouldn't be possible to take a sword and simply use it as a peg leg unless it was built for that purpose.
That's not to say that someone experienced with repair couldn't manufacture a sword into a makeshift peg leg on the fly (using rope or other materials to secure it in place, and making an appropriate skill check), though it would be difficult to balance and stand on, and should incur penalties to Reflex Saves, Attack Rolls, Armor Class, and anything else that would require stability.
