Instructions
Paw-print stamps are a rare drop, and it can be frustrating to try to gather enough to upgrade your weapon. Since they are most commonly dropped by Melynx, an easy way to get a large number at once is by downloading and completing the "Two Colors of Meow" quest, which will send you up against the monster cats and will yield a large number of paw-print stamps.
If you do not want to download an extra quest, you can go up against Melynx and Felynes "in the wild," but keep in mind that this is a very rare drop, so you may have to go up against them several times before you even get one paw-print stamp. There are three Melynx in area nine that will respawn each time you leave the area. Kill them all at once, collect the drops, then leave the area and repeat as necessary until you have the necessary number of paw-print stamps.
With both of these options, it's important to remember not to bring any items with you. Melynx steal items from you, and it's very easy to end up losing any items not stored before you go up against them. You can also gem your armor for anti-theft to protect yourself.