After every battle, you must repair all of your weapons that you have used, or else you may not use them for the next battle.
You must also repair all the weapons that you have gained, whether they have been used or not.
Kunai:
1 Ryo per repair
Shuriken:
2 Ryo per repair
Katana:
16 Ryo per repair
Giant Shuriken:
40 ryo per repair
You must also repair all the weapons that you have gained, whether they have been used or not.
Kunai:
1 Ryo per repair
Shuriken:
2 Ryo per repair
Katana:
16 Ryo per repair
Giant Shuriken:
40 ryo per repair