Can you put enchantments on Shurikens that specify being allowed on thrown weapons?
Or, more specifically, can I put Sharding on skurikens?
Although shuriken are thrown weapons, they are treated as ammunition for the purposes of drawing them and crafting masterwork or otherwise special versions of them, and of what happens to them after they are thrown.
Restriction This ability can be placed only on melee or thrown weapons.
(sorry, I only found the OGC online reference for this enchantment).
No, you cannot add "Sharding" to your shuriken.
I think "for the purposes of... crafting... special versions" means you enchant 50 at a time, not that they don't count as thrown weapons for what you can put on them.
I think the point is that
which would apply to shurikens. Furhermore:
The duplicate gains a range increment of 10 feet for this purpose, but uses the same proficiency and otherwise functions the same as the original weapon.
This includes magic weapon bonusses.
Getting 50 "infinite use" +5 shuriken for the price of 98,000 GP instead of 50 "normal" +5 shuriken for the price of 50,000 GP makes a difference. In other words: "throw" (or, more likely, shard) 100 of these, and you are in the positive.
Yeah, I don't think sharding works on shuriken.