Here's something that annoys me to no end: those spells in RPGs like sleep and instant-death that sound really cool, but the only place you'd ever actually want to use them would be against bosses, so of course they don't work against bosses. I can understand that bosses are supposed to be difficult and that letting you use instant-death spells against bosses could detract from the balance of the game, but at least be honest about it! Let me know difinitively that the spell will never work against bosses, so I can stop getting my hopes up! Say, in the description of the spell, "This spell doesn't work against bosses, so stop trying you naive little man."
What annoys me further is that more often that not this sort of spell doesn't even work against normal enemies. Go figure.
I recently played through Resident Evil 4, and it was a pretty good game. It wasn't spectacular from start to finish, but one thing I absolutely LOVED about the game was the rocket launcher. I bought it with no specific intention, just the general feeling that it would come in handy later. It seemed like a waste to use it against normal enemies, so for a while I just held onto it. The next time I came to a boss, I pulled the sucker out. I thought to myself, "no way is this going to work." Not only did it work, it killed the boss in ONE HIT! And it wasn't some pitiful mini-boss either, it was the real deal! What could have been a long and painful battle was over in ten seconds! I thought to myself, WOW! The rocket launcher ACTUALLY WORKED, against a BOSS! As powerful as the item was, it did NOT ruin the balance of the game in any way, because it would be prohibitively expensive (both monitarily and in terms of inventory space) to use rocket launchers against ALL bosses. The rocket launcher effectively let me PICK MY BATTLES. Cool-sounding spells in RPGs should work this way. They should work against bosses but there should be some force preventing you from overusing the spells. IMHO