It's a bit apples and oranges there.
The Zesuaium sword is pretty much a monomolecular blade... so it CAN practically cut through a whole lot of stuff without losing its edge - thanks to it being in zesuaium. The only thing it can't cut through is zesuaium.
The blade still has an angled surface, though, so it still faces a degree of resistance. That resistance ends up being why you still have to strain some to chop through material, but with a neko's strength (not NH-27 exclusive), you can chop through pretty much anything man-sized, yes.
However, NH-27 strength or not, a zesuaium shield will stop it cold. Also, the blade being made of zesuaium doesn't stop an aetheric weapon like the Aether saber-rifle from turning it into so much slag.
I think the bayonet you speak of is closely built around the same lines as a Aether Shock Array. I don't think Sumaru's sword can be used like one - it wasn't built like that.
The forearm equipment holds two advantages. The first is that in using the energy swords (which is really a focused torch like effect focused into a particular shape), your swings can't be blocked by zesuaium - it's a stream of energy - and it'll destroy zesuaium on contact along with having some very mean chopping power, with whatever is around the place chopped really superheated. The second is that the forearm energy barriers can block both aether and physical attacks like Sumaru's Zesuaium katana.
So, Sumaru's sword is good. It can clearly chop through a nekomachina wherever it hits. However, the nekomachina can block or parry with their shield and saber-rifles - and if they have their energy swords active on the saber rifles, any parries will destroy Sumaru's sword.
My guess is that you're contemplating using the forearm shields and the zesuaium sword (so to keep forearm shield power high). The idea would be decent on anything not using aether or relying on zesuaium protection - the foremost concern here, I think, is that Sumaru's ceremonial blade probably wouldn't survive the fight.