[Autumn]

We were on a breakthrough but never ultimately came to a decision, how about this as a final note:

Hikage gains 50% fire atk on hit
Tsukikage gains 50% water atk on hit

Hayabusa new set effect: "Ignore Fire and Water absorb/immunity"

I don't feel this will be unbalanced if Hikage/Tsukikage retain their fire/water damage types, as you'll absolutely need to dual wield these you cannot exactly abuse any fire/water spells.