I keep reading about armor imbuement changes coming, but I can't quite decipher what that means. Does it mean that all armor slot pieces will be getting an imbue, or were there some tiers that couldn't already imbue the chest and leg pieces?
It seems to be an ongoing process. Last Game Update we saw a total weapons revamp that added an addition imbued ("Blessed") to weapons. On Domino's stickied State of the Tradeskill post she also talks about adding imbues to the "specialty" armors that didn't get it.
Not all chest and leg pieces are imbueable in all tiers yet. For instance, in T4 Feyiron Vanguard Greaves and Cuirass can be imbued, but Feyiron Plate Greaves and Cuirass cannot. Tier by tier, Domino's adding imbues to all the non-fluff chest and leg pieces for all tiers (except 1, obviously).