Here is the list of (re)enchantments you can obtain on the gear.
Note that the Legacy and Crest cannot be re-enchanted!
Like gems, you cannot get the same enchantment twice on a gear (you may get STR and AGI but not AGI twice).
Shield DEFis a special enchantment that only Warriors can obtain on their shield.
It increases the Warrior’s Physical and Magical Defense by 25% when it procs (the Shield DEF increases with STR and the Enchant on Shield, at level 60+ it can be around 35% by stats and an additional 7~20+% by Enchant).
When you re-enchant your gear, all the enchantments have the same probability to be obtained (but there are 5 elements resist, so the probability to get one of the elements enchant is 5 times higher than a Crit rate for instance)