This weaponskill's original name in the Japanese version is: 弐之太刀・鋒縛 (Ni no Tachi: Houbaku)
"The Second Style of the Tachi: Binding Point"
It's derived from 鋒：kissaki, the point of a sword, and 縛(る）：shiba(ru), to bind, to tie.
Hobaku refers to a section of Isshin-ryu kusarigamajutsu, the teaching of the art of the Japanese weapon kusarigama, a sickle and chain. Included in this training is hojojutsu or torinawa. These styles revolved around restraining a person, specifically by rope. More modernly used as training for law enforcement. Although rope has been long replaced by handcuffs and chains, it is still identified by restricting a person, therefore "preventing them from acting," as is the effect of Stun (the weapon skill's effect)- binding in place and preventing from taking action.
A connection could be made to the type of weapon identified with such training, a sickle and chain. Sickles, or scythes, identify to Dark Knight. Chains, of course, point to torinawa.
Great Katana skill level 30 is obtainable by the following jobs at these corresponding levels: