Which is precisely what my first post in this thread meant.
Discussing which of the two rules is violated first is pretty pointless.
For the exercise as a whole, I'm not a huge fan of even trick parties that contain multiples of the same character.
So I'd want a bard/voice of thunder, an invoker/devoted orator, an elementalist/lyrandar windrider, a thunderborn barbarian/building thunder all wielding crusader's weapons and Pelor's sun blessing, all with resounding thunder, all cherry picking their best thunder powers, with a swordmage morninglord who admixtures thunder onto Sword Burst rounding the party out.
But I suppose that's just me. Vestige locks aren't worth the vuln 5, as all of their powers are single target and mediocre, but thunder's emphasis on massive burst sizes pairs very well with tapping radiant vulnerabilities, given the ability to use crusader maces as a weapliment (which admittedly eats up almost everyone's MC. At least avenger and cleric MCs are top-notch).