In 1P, you will need to fulfill a character's unique requirements in order to get his/her last (5th) weapon. But using 2 players, you can use a character with an easier requirement to get another character's last weapon. For example, Sanada Yukimura's requirements are really tough. You can get his last weapon in any other character's story using 2 players. This is obviously not intended by the game because you are getting the ''wrong'' 5th weapon.
1. Choose Free Mode. Hard or hell difficulty.
2. Choose the character you want the 5th weapon for as 1P.
3. Choose the character you're most comfortable with as 2P.
4. Choose the stage in which 2P can get his/her 5th weapon.
5. Fulfill 2P's requirements to get his/her 5th weapon.
6. When supply team appears, let 1P take the weapon dropped by its captain.
7. Finish the stage, and you'll find that you got 1P's 5th weapon instead of 2P's.
