10% Magic Foe would mainly be to nail-in-coffin the BRD+MCH "meta", BRD as presently designed will and should always be the speedrun pick over MCH as presently designed - BRD has more group synergy upsides/downsides, so it's worse for rando pugs and better for dedicated speedruns - so nothing would really change there. But yeah I'd be equally happy with 5% for everything. It was just thinking SE might wish to deal with the all-physical issue.

As for Battle Voice, the main thought that comes to mind would be "reduce the cooldown of all songs by 20s", still on the 180s cooldown (if not longer), which would give BRDs some capacity to shuffle their song order mid-fight. I'm sure there's some kind of dps gain there somewhere, but optimizing BRDs already manipulate WM uptime vs. buff alignment vs. clear time to some extent.