Different grinders?

[D14BL0]

I'm playing through the EN demo and I noticed something I never noticed on the JP version. When grinding weapons, it asks you to select what grinder to use. Does this mean there's more than one type of grinder, or any other item you can use to upgrade a weapon? I've never noticed it, myself, nor have I played PSU, so I'm not sure if this is just a pointless, extra menu or if there's actually other items you can use for upgrading weapons. Can anybody shed some light on this?

[Amherst_Wind]

Its most likely a formality carried over from PSU (where there are multiple Grinder types).
It at least serves to show you how many you have before you grind a weapon.

[D14BL0]

That was what I was thinking, because in the entire time I've been playing the JP version, I've never seen any other item in that list.