[Facts] Re: How wrong is this invented name?
I think it's imaginable. But I think it depends on when the story is set, and how realistic the setting is. It would be much harder to suspend disbelief about a person named Isiva living in a realistic contemporary world, than it would be to do so for a character in a necessarily fictionalized medieval setting with the name's meaning being relevant to her characterization. If the story is set in medieval times or is fantastic in some way, you're already using a lot of imagination, and the invention wouldn't seem nearly as intrusive and phony as it would if you were to pretend it is a modern name with a contrived etymology. This is just my opinion, of course.
- mirfak