This also appears to be the case with other set/leg items in other slots as well. Tal Rasha's Allegiance and Zunimassa's Trail also do not display the +element damage that they add.
Possible Auction house bug #2:
When using a 1 handed sword weapon, the auction house will compare it to and recommend 2 handed sword weapons. (Could we possibly get the option to filter recommended items by item slot/type (Glove/belt/pants) and quality (Rare/Legendary)?