The phrase "provide with a barb" means to add a sharp, pointed projection to something for the purpose of catching or piercing. There are several synonyms for this phrase, including "armed," "spiked," "pointed," "barbed," and "studded." These words all convey the same sense of providing something with a sharp or pointed feature. Other terms that could be used to convey a similar meaning include "enhanced," "fortified," and "strengthened." Whether used to describe a weapon, a tool, or a piece of equipment, providing something with a barbed feature can make it more effective and useful in certain situations.