Who am i The bite my bare body but i do not harm anyone unless they cut me first but then i soon?

You appear to be describing a "knife." A knife can "bite" when it cuts into something, but it doesn't inherently cause harm unless someone uses it to do so. The phrase "unless they cut me first" suggests that the knife only becomes dangerous when it is wielded against something or someone. Ultimately, it serves a purpose for cutting and preparing food or other materials.