Yeah I thought the aggro system was a tad weird. Then again, I'm not entirely sure how complex the system is, but I tend to lose aggro rather quickly. But I'm glad to hear you're enjoying yourself, and I'll keep at it. I like tanking so yeah!
Funny, right after my post I decided to change things up. I saw a wizard/rogue were trying to cap our closer node so I made it my mission to hold that node alone. The wizard pretty much couldn't do anything to me between lunges/stun/block. The rogue was more trouble, but I did alright.
If I'm with the group I try to focus less on supporting with damage, but rather through mark/stuns. Seemed to work ok.
CC heavy matches are frustrating, but I think I'm getting the hang of it.
EDIT: Does enforced threat doing anything special in PVP? Is it just marking targets?