There's a fkin reason why Yumi is 1 slot. After all it doesnt matter really as there are 0 slot weapons anyway now. However Yumi is meant as a HA bow in first case. And HAs need more arrows than any foot archer.
It doesnt matter if some stupid katana guy can take it plus the katana. Who cares about that. Anyway, 2h GS + Long/Rus Bow doesnt fit anyway. You'll never have enough wpf for both (or even stat points for a good build for both ranged/melee).
Did you even ever play with Yumi? While being on foot you really wish to have any other bow. Yumi is great on horse but awful on foot.