Mantled Warrior acf from Mind's Eye is worth it, along with Substitute Powers on the Mantle.
Normally you'd trade one Mantle for two Expanded Knowledge feats.
You come out ahead by one feat, and lose that one feat advantage,
on the acf sub on the level 2 bonus feat. Still the power selections
can be
at level instead of level -1.
And it expands the psywar list into 7s 8s and 9s.
Use Powerstones like a caster use Scrolls above level.
PsyWar gets the ML for it, even though there's that minor brainburn chance.
Or with Magic Mantle, you could qualify for Nar Demonbinder ...
If you aren't or can't use Substitute Powers, it's not worth it.
I don't remember anybody getting any mileage out of Mantled without it.