[BlKnight]

Like Locke Boy said except:

-It's the square root of how many upgarde slots you want on the weapon, when you use prepare weapon you can use diamonds to add slots, it's better to save up diamonds now and buy as many slots as you can (say /skills to see your max) anyways so 36 diamonds gives you 6 slots, 9 diamonds is 3 slots, etc.

-Make sure the weapon is on your good account when used, once you used prepare weapon on an item it becomes a Youname's Weapon and can only be used on that account