Armorings: Are and have always been bound to that slot, if a you remove a armoring from a headpiece you cannot put it into pants/bracers/belt/offhand/gloves etc. However armorings from Belt, Bracer and Offhands are not bound to any slot and can be placed in pants/gloves/head/chest and so on.
Mods: Havn't and still arn't bound to any slot, so you can pull out a mod from a mainhand and put in your bracer/offhand/head/chest etc.
Enhancement: Same as mod
I hope this cleared up the questions you have.
Actually this part is False, when the game first came out you could pull out Armoring mods from items and they were NOT slot specific, a little ways down the road, when Battlemaster gear got a slight boost during patch 1.2
in which all "endgame" armorings could now be extracted but were bound to slot. So there was a brief time where you could extract a helmet armoring and place it into a belt, but that is a thing of the past.