Brand of Arcanus not working

Spellblade’s Brand of Arcanus node on the Firebrand spec tree doesn’t seem to be working. When I build stacks of Firebrand I’m not getting any additional spell damage.

the node itself doesnt actually do anything atm and firebrand behaves as if it didnt exist still giving u melee damage instead of spell damage and im assuming the crit multi also doesnt get applied either