lmaooo its super funny but there needs to be a believable reason why he cant control his skills right... dont think it has been mentioned yet
I
think (but I'm not 100% sure) it's been mentioned that the Ultimate Martial Arts skill essentially wired itself into his muscle memory, which is something you train so you don't
need conscious control.
A real fight with weapons rarely lasts more than 5 seconds and are often only a single exchange of strikes lasting
maybe 2 seconds, so the time it takes for the brain to go "okay, I'm going to make a downward diagonal slash; if they block, I'll follow up with a wind into a stab; if they deflect, I'll come back with a rising cut from under their guard" to the muscles actually putting that into practice is a small eternity.
If you can more or less cut the brain out of the equation and let the body do its thing, your responses become
much faster.
In Yuuji's case, he has the muscle memory without the training, so his body basically acts on its own as soon as he picks up anything that could be vaguely construed as a weapon.