I stumbled upon it when looking into other modern fighting techniques like Israeli Krav Maga. There is an acronym "unibos" which would translate into "universal fighting
system(a)" and is basically a fluid motion based fighting system unarmed, with knives or firearms. Actually a video
like this one demonstrate it well and the explanation in anime about seemingly weak attacks that feel powerful must hold some truth because
in this video some attacks seem like bullshit, yet people get knocked down.