Vanguard weapon models already cover the "pure energy melee weapon" thing, albeit not for all of the powersets you listed.
"You don't lose levels. You don't have equipment to wear out, repair, or lose, or that anyone can steal from you. About the only thing lighter than debt they could do is have an NPC walk by, point and laugh before you can go to the hospital or base." -Memphis_Bill
We will honor the past, and fight to the last, it will be a good way to die...
I'd suggest swapping to a Dual Blades/Fire Brute. It's quite bad-A.
The white hot searing flames of Justice contrast well with the black burning fire of Judgement. You can go either way. My Brute, Nickel-Mage, often switches between swathing through hoards of sinners using Judgement and cleansing their souls of impurity using Justice or allowing the heat of their sins burn them to ashes while subduing the wicked with luminous blades of absolving fire.
In other words, color your Burn dark and your blades white or vice versa and your character's body vanishes in the flame but you can still see the swords slashing about.
The Vanguard Blades are your best bet but Dual Blades gets 3 versions, the Katana glowie blade, the Broadsword straight glowie blade and their own pure energy glowie blade. Burn helps to 'catch your swords on fire'...
give us the option to have our katana, DB, mace, axe, TW, staff, etc all made out of pure(tint/colorable) energy, and leave us the option to pick light or dark as well.
Also, let us apply any of our current unlocked auras to our weapon, Please. I want to make fire blaze off my sword for my katana/fire brute.