u can say the same abt brook , he summons ice from hell through his devil fruit
but thats still accounted as swordsmanship
" observe the freezing blade "
speaking of brook , he literally stated music to be a sword skill
" witness my skill with the blade " he says right before stringing his guitar
all he did was string his guitar with his sword , the attack didnt even come through that
it came from his guitar
u can say the same abt fujitora's meteor strikes
he uses his sword to activate the gravitational pull ( stringing the guitar )
the devil fruit then brings a meteor down ( the guitar )
the meteor reigns down as an attack completely different from a blade move ( music in this case )
yet its presented as a sword skill , as ridiculous as it might be .