Even the methods they exploit Constitution or Charisma for their power can be melded into very interesting flavor.
Constitution can be percieved as
- Using there own life force the stronger that life force the mightier there power
- perhaps this life force is in promise of the future gift where the quality of their eventual sacrifice to their pact holder is based on those life energies
- Constitution may represent resisting of pain I mean the idea that the alien power source they draw from is painful and your ability to resist that pain governs the control you have over it.
- having the will to resist the pleasure which channelling your power induces.
- clever bending of the rules of this universe (I would love Arcana to be based on charisma for this one).
- tricking/seducing the other worldly entities in to giving you power they dont necessarily want you to have.
- The voice of power - many warlock powers are psychic and remember communication is a medium of control - perhaps you were chosen to be the voice of this other world entity and your ability is entirely eldritch charm.
I will also be compiling and presenting inspirational flavors and descriptions for specific powers
- Glare of the Possessed : An intimidating roar mingled with a spirited slashing attack and your enemy cannot resist drawing back.
- Otherworld flames: I wreath my weapon in flames in which you can see other worlds if you look closely enough - space itself warps and slides my enemies back when the flames lick them.
- Slash to the Knees : Nothing special I try to cut his legs out from under him and he staggers back
- Saurons Smash : With each hit a boom presses the enemy back