Item Upgrades!

[fangless]

2h gets more benefit since they actually use Obliterate as a main attack, whereas DW is using Howling Blast more with those runes.

At least, that makes sense in my head :P

[Shiira]

Indeed, 2h frost uses attacks that scale with weapon damage more often, so it will benefit more from having a higher item level weapon.

On the other hand, dw frost doesn't suffer as much from having low item level weapons because much more of its damage is just based on ap.