Having sharp teeth means something similar to what what it means to “have teeth”, only you’re a little more cruel with the way you do things.

When someone says you “have teeth,” it means that you show that you actually have the power you do as apposed to saying that you do. For example, if you threatened to cut someone off for repeated violations of your social circles rules but you never did it, then you would be considered to have no teeth. But if you said “this is your last shot” and once they blew it, you cut them off, you would be showing that you have teeth.

so having sharp teeth means that you not only have the power to show for what you say, but that you are merciless with it and are unlikely to give any second chances nor leave room for any form of atonement or making up for your actions. More often than not, it means that you do more than just prove the power, you also tend to abuse it simply to prove a point or get a message accross.
“Damn, did you hear about what happened with Josh after he fucked around with Sammy’s guys? The dude has some really sharp teeth, Josh definitely won’t be doing that again any time soon.”

“You’re one cold hearted bitch to show teeth that sharp.”
by gangterminology.net September 5, 2018
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