The weapon heirlooms didn't really change after the reset.
All shield stats drastically changed after the heirloom reset, not just a single point here or there.
Shields really need to be looked at again by the item team since I believe they were inadvertently nerfed instead of buffed as was intended.
If i gain 3 cut 2 pierce and 2 speed before change and only 3 cut 2 pierce and 1 speed after change the impact is as big as your shieldchange i guess.
About 15% worse then before.
I dont want to say that shield hasnt lost more but swords lost not only a little bit.
In addition all my clanmates wearing shield love their heirloomed shields so it cant be that bad.