I'm relatively new to all this vanilla stuff, having played only for about 3 months before TBC. So I have no idea what items, or rather.. enchantments are supposed to be in the game during what patches, and which ones aren't.
That being said, I recently(as in yesterday) finally acquired a weapon worthy of getting an agility enchantment on it. I disenchanted quite a few greens on my lower level warrior, and poured an extra 10g into it from AH mats just to get it....
And today it's gone. I had no idea that this enchantment wasn't supposed to be in the game, and now I want to be reimbursed for this stupidity. That's roughly, what 25-30g worth of mats that just got trashed overnight, I literally had the enchantment for less than 12 hours.
Yes, before anyone mentions it. I did see people in trade saying to 'get your agility enchant before it's gone' but I assumed that meant that the enchantment itself would no longer be available to enchanters, and any weapons enchanted would keep said enchant. Sometimes things like that do get removed for 'balance' reasons.