The main problem I see with this does apply to all non-knife melee weapons. They are strength-based, while most of the Scoundrel skills are dex-based. So, you would have to advance both strength and dexterity whereas ability points don't come in large volumes.
On the other hand, you would gain the option to skill the strength-based Man-At-Arms skill tree next to Scoundrel. A 2H assassin would most likely lack in toughness to be a tank, but I myself played through D:OS EE in classic mode with a friend with "only" a Scoundrel, a Ranger, a Mage, and a slightly reinforced Inquisitor, and we managed quite well. You'd have to modify your tactics to compensate, but fortunately, D:OS offers the liberty to do so.
I didn't try your combination myself, but I think you should be able to finish the game in classic mode if your other characters are reasonably capable and your own tactical skills are reasonably developed.
