You can never beat spoilers.

tell what? that its a weapon? i think most of us figured that out when hes slashing ryuji with it

Aiko, everyone knows:

1.) its a weapon
2.) its sharp
3.) its knife-like
4.) Shinkurou inherited it from Houzuki clan
5.) they "installed it" into him
6.) he refuses to use it even when he was getting pwned (which is contradictory from earlier episodes)

Besides what we already know from animu, we don't know:

1.) Why it comes out like a unwanted erection sometimes
2.) So its a blade...what's so special about it? Its just like any other knife/sword. Big deal.
3.) Is it part of his bone or something?
4.) Everyone in Huozuki clan have it ?

Fyonne: Manga never explain? I tot u following its.

And the way u describe, sounds like Houzuki clan is part of Weapon X programme.