So 2H benefits more from using ilvl upgrades on your weapon than DW does? I have 463 blue weapons, so it would just be a matter of having 3k jp or 1500 jp.
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
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.