Each weapon upon being picked up will supply 20 of that weapon.
Does 1 bar of damage. Travels all the way across the screen.
Triple shuriken - Same as shuriken but you get a three-shuriken spread. Since they're better than standard shuriken, they're less common.
Does 1 bar of damage. They only travel a short distance before going in reverse. If you catch it, you regain it. If you don't, it travels across the screen exactly as a shuriken. If you switch characters and catch the boomerang, that switched character will obtain the boomerang, replacing other inventory.
Does a whopping 2 damage. These scrolls only appear in certain locations and cannot be retrieved by enemies, unlike the other 3 weapons. They travel across the screen and covers a wide range. The best weapon in the game.