I shall harm you with a bladed object, preferrably with a "switchblade" or a "butterfly knife".

i will stab you with a sharp object. the person or persons being stabbed will usually be of latin origin, as well as the stabber.

A new greeting for the ages.

I shall cut you, sucker/tool/buffoon.

I shall cut you with a bladed object because you are a moron/bonehead/idiot/buffoon/tool/person who slept with my mother or sister or girlfriend (or father or brother).

I've got your back and will fight for you, protect you, whatever goes down. No matter what. Ride or die. "I will cut somebody for messing with you."

If you cut for a person you feel them, you almost love them..i;e This slang originated in Texas and has spread across the dirty "I cut for you!"