The only weird ones I'd say are H:Guren, H:Senei and Shoha, Shoha II.

Guren has drop off damage for secondary targets and Senei just does a little more damage and is available 2 levels later while sharing a cooldown between each other, realistically speaking at level 72 instead they should just increase the damage itself for the main target and keep a similar drop off damage. The same treatment should go to Shoha II which is another attack that's practically the same thing (Mediation Dump) so having it do the full 580 to the main target and then X% to all secondary targets would kill off 2 keybinds. Outside of these two clashing pairs there isn't anything else that really warrants sharing a bind.

The rest of the abilities all have their use with Fuka, Oka and Mangetsu enabling you to have an AoE combo and get the 2 sen required for Tenka Goken use in 3+ target situations.
Namikiri could technically replace the button that Ikishoten occupies due to it being the condition to use it entirely.

Right now I count 34 binds for all the sam actions and sprint on my own keybind set-up, which is definitely managable with proper keybind set-up and the use of shift modifiers alongside a mouse of choice with an extra 2-12 buttons (there are many solid gaming mice that have 6/8/12 extra keybinds on them alone without accounting for shift modifiers) which isn't entirely out of place in terms of keybinds required to play an MMO.