The addition of a “Only Show Usable” filter would make using the trading post much simpler. This would hide things like light/heavy armors, rifles, pistols etc if you were a ranger. At the moment you need to either know the name of something you are looking for or trawl through pages of items if you are just looking for example, a coat where 2/3 of the items available are not actually usable by you.
As an alternative, at least the introduction of a light / medium / heavy filter as, as when replacing your armor after 10 or so levels, it is more use to just see all the lvl xxx medium armors than it is to see all the lvl xxx gloves