It took a few years, but we finally cracked a workaround to let people get experience from more than just killing mobs. Two new options have become available:
A personnel trainer stands here, helping you gain experience.
This man in Four Kings has a selection of quests for level 15 and higher. Please note that there are three tiers, so the quests that yield an exp reward at level 15 will not yield a reward at level 26. There is also a selection of quests for level 35+. He asks for specific samples, so it shouldn't award for a two-headed serpent slain in Mayene, for example.
Say "quest" to get him started on a list of available targets, all of which can be found around Andor/ Braem/ Kintara/ Caralain Grass/ Black Hills. This is in line with making Andor a more bustling place again.
An artifact collector stands here, searching specific items.
You can find this collector in Falme, Amador, Four Kings, Fal Dara and the Ruined Keep. Say "exchange" or "trade" to get him to talk.
This man takes crossrace trinkets and awards exp for them. E.g. a human can't turn in a warder cloak, but DS and SS can. He takes both rank 1 and rank 5 trinkets, awarding more for the latter.
Simply give him the item and wait a few moments. He will drop the item if he has no use for it. With so many clantrinkets I suspect there may be a few that I missed, if you feel he should accept something, please post on Bugs.
-Both- of these features are somewhat limited by the max exp you can gain per any given level, so turning in a rank 5 trinket at level 10 won't magically make you gain 15 levels, simply because it cannot award the same amount as if you were level 40-51.