[quote=Lucius Cypher]
That implies that this character was spliced to a living person. She only has extra arms, unless limbs carries the souls of people too. And note, in the backstory I have written in mind, these were fairly normal humans; no one of any particular unique ability was chosen, just anyone willing or available was experimented on. Those willing wasn't put through a mad science experiment so much as a rather mild-manner experiment operating on a very mad idea. It was free game on those simply taken, who were usually vagrants or wanders.
[/quote]

One human soul cannot operate extra limbs, only the things they were born with. You could graft additional limbs to a human without the other soul but they wouldn't be able to operate all four (or more) of their arms, just two at a time. Imagine if you suddenly grew two more arms. Would you be able to use all of them? you wouldn't have the instincts for them. In any event, you'd have to kill two humans to get their parts as nobody has figured out how to vat grow parts, and magically created ones don't... look right. Never mind that these kinds of things tends to royally piss off the gods.