The name of the game with melee charmer is BUFFS. Song of Storms, Skaldic Cadence, Cadence of Power, Sorran Chant, etc. Pump your sexiness and use it to apply a bunch of buffs so you hit harder.
Once you get Expert Inspiration, this becomes a lot better. Especially because EI applies to all powers, not just charmer powers. You can have stuff like Blessing or Shielding Smite up for two turns instead of 1.
Serpent's Dance is okay, but I think Cadence of Power or Skaldic are better personally. Jassiran Glaive and Ashelander/Rosebloom Shield are good weapons for this.