So, the combat in my game is starting to get slightly stale for my tastes, and I've always been slightly irked by how much better deceptive attack seems compared to a feint- the improved turn economy of deceptive attack is highly desirable.
A feint, done right, draws your opponent into a state of weakness so that you can then smash in their face, taking advantage of it.
My thinking is, a good enough feint might open up a hole in an enemy's defense so glaring that even allies can take advantage.
Proposal:
Any feint that imposes a penalty of -3 or more to a defense roll can be taken advantage of by allies, not just the combatant who originally used feint.