Played 8.1 as a threat tank (paladin?), here are my 2 cents.
Since I am inclined to not lose fights than to win quickly, turn economy is more or less ignored in this setup.
If anyone wants full threat control (to self) then the new "Endure" ability straight up gives double "Vanguard" threat.
It also heals for 50ish% then regen 10ish% afterwards, so losing durability from "Vanguard" would be acceptable
If you ever lose control of threat, then "Lay on Hands" would be useful. However, I doubt any companion could generate enough threat to ever warrant that.
(the only time my companion actually overtook me was when I used spellblade Cait and spammed "Charge weapon" on a group of imps)
When enemies are dealing too much weapon damage, swapping your At-will to "Deflection" is going to help immensely.
(There was exactly ONE encounter which screwed me over, and the silver bullet was "Deflection". I actually reset multiple times to make sure I never lost against it.)
"Bark skin" and "War banner" if you need extra healing. Honestly, your job as a threat tank is done after pressing "Endure" most of the time. Therefore, encounter and recharge is free to choose. Personally, I use lv6~8 summons + "Empower Summon" for extra damage. Preferably an AoE mage/charmer.
I have no recommendation for ults due to them being pretty bad.
"Unbreakable", "Revive", and to a lesser extent "Inspiration", requires your party to be near destruction to be effective. You probably lose that fight anyways.
"Abjure" is pretty effective (3 turn stun + disenchant is always good in any game), so I choose them for tougher encounters.
For companions, I take Spellblade Cait for single target burst + dps, and a situational. Agni is a personal favorite due to her 1-click nuke, nice set of buffs and giant heal. Funny build is to take Rimebound Cait and attach Rime veil to PC. Especially effective against cultist barghests. Why are you hitting yourself