A professional weapon is a tool used in a specialized trade that nevertheless has tremendous damaging potential. When using a professional weapon, you gain a +2 insight bonus to checks with the listed Profession skill (or to checks with similar skills that could reasonably use that weapon as part of the profession, subject to the GM’s discretion). If you have a number of ranks in the listed Profession skill equal to the item level, you are considered proficient with that weapon, even if you would not normally be. This proficiency never counts toward prerequisites of any kind.