When playing a Vanilla-Vampire I never saw the need to got for a One-Handed and Magic playstyle. Switching between dual casting destruction and illusion spells and wielding a massive Two-Handed sword sounded alot more appealing to me and it worked out quite nicely. Doing so however gated me from using the weak yet signature spell of vampires - Vampiric Drain.
The idea for this weapon came when I closely examined the way the unqiue Dawnguard Runehammer functions. That was the basis for this weapon.

Vorador is a Silver Greatsword that can unleash life-draining energy waves by block-bashing. This consumes a small amount of additonal Stamina. The greatsword's base damage is 20, the vampiric wave absorbs up to 30 health. Multiple enemies can be hit, making it an efficiant way of sustaining while having both hands occupied. Additionally, Vorador can be enchanted like any other weapon and has inherited the nature of Silver Weapons, dealing increased damage to other undead creatures.

You may either use the Console to get the weapon on demand (type in "help Vorador") or play through Dawnguard, as I have added it to Lord Harkon's inventory.
I should also mention that the weapon purely relies on vanilla assets and can easily be configured in the CreationKit.