Shield Arm?

[Luke Styer]

On Sunday I ran my first encounter with an Iron Warden swapped in for an Iron Golem in a pre-remaster adventure, and I noticed this new ability:

Iron Warden wrote:

Shield Arm The iron warden has a shield built into its arm, that it can use as a steel shield (+2 to AC and Hardness 5). Because it's a part of the iron warden, all damage in excess of its Hardness is dealt only to the iron warden.

This made me wonder whether a magic prosthetic arm with that same functionality would be workable. Aesthetically, I don't imagine a built-in shield, so much as the wearer just using the arm itself to "parry" and block. So basically a weaker Indestructible Shield, that still leaves the hand free.

Would this be either (a) too good at a level at which a 5 point shield would be worth bothering with, or (b) not good enough to be worth bothering with at all?

Should it grant the Shield Block general feat? Would having it grant Shield Block only using the arm itself be too fiddly?

[Teridax]

I think the assumption is that an adventurer would simply have a prosthesis equipped that they'd use to wield a shield. I do think there is room to have more equipment built into prostheses (that's the basis of the immovable arm, for instance), but with shields I think it gets slightly tricky, because shields by default are meant to take damage and even get destroyed. The question here is: if the shield arm gets destroyed, does this destroy the prosthesis as well? If so, then an adventurer may be hard-pressed to pick this shield arm when they could just wield a shield with their regular prosthetic and not lose their hand if their shield gets destroyed. If the shield itself can't get destroyed, then you have effectively an 18th-level rare item built into your prosthesis, which would make it either difficult to access or potentially build-warpingly strong at lower level. A compromise there could be to let the shield in the arm get destroyed without affecting the prosthesis, and this is something the foldaway trait could help with very nicely by letting you integrate a retractable shield into your arm.

[Perpdepog]

I'm in agreement with Teridax that one of the points of a shield is that it gets destroyed if it is used to block too much, and skipping that step is potentially asking for trouble.

I think you might be able to get a shield arm though, if you focus on the arm more than the shield. For example, your idea of an item which grants the Shield Block feat with itself could work. The conceit is that you slot a shield into the arm, and the arm takes care of defending for you, even if you don't quite know how.
Another thing to consider is that, perhaps, the shield regenerates or repairs itself each day rather than ignoring damage. That could also give you the reason for wanting a shield arm as opposed to just strapping on new shields to a regular prosthetic arm.

[Zoken44]

I think the way you describe it it might be an interesting set of archetype feats for the Sterling Dynamo. Having a built in deployable shield.

[Dragonchess Player]

Note that you can probably reskin a gauntlet buckler as a "minor upgrade" to a prosthetic arm without causing any balance issues. Adding a reinforcing rune doesn't require any new rules, either.