[tehfusion]

Go to a weapon title NPC. There's one in each town. Then talk to him and choose 'register license'. Then simply place in your weapon, and a license, and click 'ok' (or whatever it says). That will apply your license to the weapon.

Notes:
-You can only have up to three licenses on a weapon.
-You cannot remove licenses (as far as I'm aware).
-You will gain a monster killer title for that license, which changes as you level it up.
-You will lose the title(s) when you lose the weapon.
-When you apply a license to a weapon, you gain +15% damage to that monster. That's an awesome bonus, especially at higher levels.
-As you kill more of that exact monster with the licensed weapon, it gains experience (you can see this in the weapon info). When it reaches 100%, the title will upgrade, and so will the damage - by 5%.
-Your weapon will display your character's name as the 'creator'. This will remain even when you trade/sell that weapon.

Hope that helps.

-F