I don't know what Kamihime you have (I only remember something about water from our last talk), so...
I am not sure about Odin hitting harder. Yes, she's faster. Yes, she has more combo rate (at cost though). And yes, she'll probably hit much harder at 1 HP. I think that Odin and Shiva are quite different though (Odin is fast suicidal kamihime, while Shiva is mainly nuker), so it's hard for me to compare them reliably (even more so because I don't have Odin).
In general I only gave suggestion, because you've said that your water relies on debuffs (which suggested team have... not that many).