The Forgeborn and Heavy Shield passives of the shield throw skill are both listed as increasing the fire and physical damage, respectively, of the skill shield throw. Putting points in either doesn’t affect the tooltip. This prompted me to test if they worked and so I stripped down a naked character to test on the dummy.
I put points into shield barrage to make the cost of the skill zero and spammable so i could quickly test but otherwise assigned no points and wore no gear. The damage range of shield throw was 35-52.
I then put 3 points into “Heavy Shield” which should increase physical damage by +9. I repeated the test and the damage range of the skill was 35-52. I repeated the same test for Forgeborn and it also showed no change.
These two passives are not currently working.