I can find uses for a lot of these items.
Instant disguise. For larger creatures, there's a lot you can do with a whole lot of bodies in your control.
Can be used as a signal, message carrier, etc. If it teleports the user, too, then battles will never again be dangerous. Don't like where it's headed? Don't be there.
Turn 10 of my coppers into 10000 Schmeks? Sure! Fuck yeah, huge source of metal or pile of coins for INSTASTAIRS.
You can use this to crack things wide open through use of thermal expansion/contraction. Also, boil your soup. Even if it becomes ice, you can keep trying (even with the same batch of soup if you thaw it first.)
Seriously, man. Infinite amounts of anything will break a game in two.
Distractions, magic tricks, etc. What happens when some of the pepper gets in an enemy nose? Logically, one of two things  the pepper teleports out to reform (Try some detect magic on invisible enemies!) or  suddenly, maceface.
Plus, scattered pepper acts like any other scattered powder. It helps with detecting invisible or hiding enemies. Pepper can also be used to wake up comrades quickly or can be thrown in enemy faces to make them pretty dang useless.
I completely fail to see how this is useless.