I think both of your descriptions of irritability are accurate--curt & snappy AND wanting to provoke a fight--but the later is the one that's out of balance and needs attention. The curt and snappy can be corrected, usually, by going for a walk and getting centered; but reaching for a knife is something that needs treatment (meds, therapy). Curt and snappy might be a warning sign that you are headed toward the more serious irritability, but only you would know if there's a connection.