I was thinking I like the idea of the vanguard, specifically, using his action at 5+ level to grant an additional bonus when he grants an attack, but he can't sacrifice two attacks like some other subclasses. Something like, "When you use your Marshal Teamwork feature (any name suggestions here would be great, I'm stumped) to grant an ally an attack, the granted attack gains advantage if it's against an enemy you're adjacent to."
I think something like that (an upgrade to the feature that grants attacks) would make sense as a 6th level subclass feature. Then the action cycle for the tier 2 vanguard is make one attack, grant one attack with advantage, use bonus action to grant bonus damage or spend TP on additional feature.