Why is there 4 ammo options for bows and blowgun?

[Goat Buster]

I'm pretty near the end of the whole game (finishing Iki quests and story) and I've still got 4 ammo options for all ranged weapons with 2 locked in each.
Is this a bug? Am I missing something? I thought it would be something I'd acquire on Iki but it does not seem so so I'm left wondering.

[We Live In A Soul Society]

There is a charm which does something related to that, if you have gone to iki and done an archery challenge, you should have it.

[Goat Buster]

Originally posted by DEMIGOD FELLED:

There is a charm which does something related to that, if you have gone to iki and done an archery challenge, you should have it.

I'll check on the charms once I boot the game next time but I can already tell you the challenge's charm is just about concentration so it's not this one.