Go to Dark Grab and enter the room with the two knights. Use your catcher and shoot them five times. They are worth 6 points each. Continue this to get a lot of points. Once you have about 30-40 of them, leave Dark Grab and go to the master's house. Develop one of your weapons and use all of the knights. This should give you a lot of points on that weapon and should be almost enough to evolve it.