It's real! There is no way to get more Shurikens in the game; the adjustment is a fairly minor one.
Master of Lanterns doesn't use that yet, but I might go ahead and apply it to her and other bosses/enemies that summon other monsters. (For the Craven Fiend, I'll probably allow some extra phantoms to spawn in, I think they have drops.)
The statue description is meant to be a reference to artifacts in Dwarf Fortress, although it didn't menace with spikes of anything.