To bad we the players didn't get to experience any that trauma.
Even the Inquisitor's closest allies and friends didn't seem to notice, Headcannon drama ... pew, pew, pew! I can sort of see Verric three weeks down the road saying "so ... going for a lopsided look aye? A bit extreme, but I see what you were going for. BTW when did you get the arm removed?" 
Well...that supports my idea that we need an armless Inquisitor in DA4. It wasn't great that there was no reaction to the loss at the end of Trespasser (instead going for the shock value which only works in the first play through), but hopefully Bio can mitigate that by having the Inquisitor discuss how they've had to learn to cope without their arm in the beginning of DA4. If we start DA4, regardless of who is the PC, with the Inquisitor just having a cool new arm, it's really like nothing happened. New players would have no clue that this person went through the trauma of losing a limb. It feels swept under the rug.
This isn't to say that the Inquisitor couldn't gain a prosthetic during the course of DA4. But I really think we need some kind of reaction to such a huge consequence of the Anchor.
Some people make to big deal out off nothing. Arm already replaced. I doubt anyone care in DA4. You lost limb in world where people can be resurrected from the dead, big deal if you someone important just go to mage "One arm please"
No one has been resurrected from the dead; that is one of the few rules of magic which seems to be constant. Flemeth has regenerated, as has Cory, but the most that could be said was that their soul/consciousness/spirit transferred to a new vessel, not that they died and came back.
I hope this never changes, as one of the major mysteries in Thedas is where the dead go. They don't exist in the Fade, they are supposed to travel beyond the Fade to another realm. Whether spirits turn out to be the souls of the dead wiped clean of memories is uncertain, but even if that turns out to be true, I wouldn't call spirits coming into the mortal world as resurrection.
Well, we have minigun in a medieval age, and it would be strange a robotic arm?
My issue is more about the emotional impact than whether it's possible to identify a suitable prosthetic. Personally, I don't like the concept sketches of IB with a cannon arm. That's a bit silly and too steampunk for the setting, IMO. And having a technological or magical unique apparatus would just exchange the Anchor for a new gimmick for the Inquisitor. I want to see the Inquisitor as a person, not a super special snowflake with a unique power.