So you're already in the last stretch of the game, right? You have your Infinity+1 sword in hand when you suddenly see a secret chest off the beaten path. You open it expecting to find the Infinity+2 Sword... only to find the Infinity-1 Sword. disappointed, you stow it away to sell off later. Outdated Innovation is when an item (usually a weapon) is only obtainable at a later point in a game (usually an RPG), but your current items are already better than it, making it effectively useless or at very least obsolete. Finding this item usually results in groans of "Gee, if only I could get this two levels ago".
Hello, Unknown Troper. You'll need to get known to lend a hand here.