Heft support is either bugged or has wrong wording.

Heft support seems to have no effect on Bone Cage and Bone Storm based on the tooltip and I don't understand why. Tag says:
'Supports Skills which deal damage, increasing the maximum physical damage of their hits'

Why would this have no effect on physical spells? Based on some other posts around the internet it seems to only work for martial weapons. If that is the case, and actually the intention too, the tooltip should be more clear. Would kinda suck though because there is hardly any gems for phsyical damage spells.