If you've been downloading the official patches, you should have patch 1.9 installed. This fixes the bugs with the Ebony Blade that caused it to benefit from certain One-handed perks and buffs. Now, it works solely as a Two-handed weapon, as it should. No One-handed perks/enchantments, including Bladesman, will have any effect on its damage, speed, etc. Just invest perks in Two-handed as you would with any other greatsword.
EDIT » Dang, double-ninja'd. I need to learn how to be less wordy. :(