What is the logic behind the Zodiac Spear in FF12?

Why is it that certain chests will cause it to not appear in the Necrohol?

How can I tell, without a guide, that a chest I'm opening is a "forbidden chest"?What is the logic behind the Zodiac Spear in FF12?
Without a guide, you don't. I think that was kind of the point: having some reward in the game for people who do buy strategy guides.



It's simply the way they made it possible for chests in different locations to have their spawn state linked. The entire random chest system was horrible to begin with anyway.What is the logic behind the Zodiac Spear in FF12?
one chest across from old dylan's house is a forbidden chess, so don't open that one. there are a few chests near where you defeat a rare game, so down open any of those 12. also, there are a few in a fortress where vaan and those two in his party are imprissoned, so don't bother open them. If you accidently touch one of them, even by mistake, go ahead open the rest, but if you don't touch any of them, you will get the zodiac spear later on in the game.What is the logic behind the Zodiac Spear in FF12?
You can also get it through a really long bazaar list. I suppose its just there for people have guides, i mean nobody in there right mind would ever pass up all of those chest