I spent too much time trying.
It is possible on Charm, but no clue about the possibility on Melee and Ranged (would result in a 20% Power buff, which makes you permanently at 720 Hero Power, so maybe that’s why we can’t)
The +10% damage only applies to the currently equipped weapon, no? It shouldn’t stack.
Guessing it’s as difficult as combination of 5% atkspeed 20% crit dmg, took me ~80 dust to roll that on a spare red trinket
Charm + weapon
So if you roll power vs skaven/chaos on both weapon, and on charm, you get a permanent 720 Hero power ^^