Answered: Martial arts movies

Hello guys, I just found your website because I have been searching for this movie for years now and maybe you guys can help me out.

I was only a kid at the time, so the movie is surelly 80's or early 90's.
It was a movie about Martial arts.

some guy is in a group/gang that just stole gold bars and lock them up in a safe for later pickup. The key was branded into the back of a pizza and each member would get a slice, so no one could go get the gold without everyone there.

One of the members starts killing everyone for their pizza slices, and the movie revolves around the story of the brother of one of the gang members and his nephews (kids to the late gang member).

His brother goes on a vendetta killing everyone to avenge his brother.
He his known to have learned a special martial art, very rare and secret.
He teaches his nephews this martial art, only when they prove worthy (trial by kneeling on a brick with their shin).

Do not know any of the actors/actress, I know that one of the gang member is a woman.
I have this faint memory that the movie took place and a island/shoreside/boats involved.

Thank you for reading all this, hope you can tell me which movie this is.