Oh thank God for this list. Trying to add haxless characters to a "most skilled" list can be hell, way too much effort just to get your favorite characters' achievements their due recognition.
Anyway, for haxless (relatively), Musashi Miyamoto from Baki deserves a high spot. Afaik, his swordless cut relies on basically abusing his opponents' own danger sense (which seemingly everyone in the Baki verse has), and essentially attacking them with such a form-perfect imitation of a katana slash, mimicking every last detail to a tee, that they pretty much placebo themselves into taking damage. That much skill and eye for detail alone should allow him a spot, not even counting his other feats.
I'll try to nominate Sekiro later, that's all the time I got for now