The only appeal of a warden's sword is the ability to cut through enchantments. That, and the durability of a metal focus that doesn't snap in half when you use it to play Whack-A-Ghoul.
Personally, I like the idea of the Winter mantle being used to supplement his staff. He could use ice to form edges along four feet of its length, leaving him a two foot handle for his ice sword-staff. Not to mention he could use ice to make it a spear, or even a sickle.
Downside would be its weakness to iron. It'd do great against creatures, but against a regular sword, he'd be in trouble. But in a supernatural pinch, it'd do.