I think it's a great name. What if you thought about it in terms of "a gift from a goddess" instead of
Isis specifically? Would that make it less weird for you? Or you could go literal and say "gift of the throne" since
Isis' name might possibly mean "seat, throne".
I always get excited when I see a name, especially an unexpected one, that references a deity, but that's because I'm a religion nerd as much as a name nerd I guess.