Nothing to do with your pet. If you put the license onto your weapon and level the license up, you can increase the damage you make to that particular mob on the license.
People usually level them a higher levels for crit rate. You can fit a max of 3 licenses per weapon. You also get it done at the NPC in Roumen (forgot the name.. I think it was weapon merchant ><)
More info
http://www.fiestafan.com/wiki/Licenses
Moved to Questions and Inquiries, Roumen Port is for member introductions.