Blashpemy not interacting with curses.

Blasphemy in my item says it's level 5, +2 from helmet, + 1 from global and it's level 2. So at level 5 it will give +1 to supported curses.

My helmet is + 2 to socketed curse gems, i also have + 2 to all curse gems on tree.

Yet my curses remain level 24 as if blasphemy does nothing but grant it aura.

The thread title is pretty misleading.

There have been many threads this league about Awakened support gems that give +1 to the levels of supported skills with the matching tag, are not granting that bonus properly if affected by modifiers increasing the support gem's level.

So your level 2 gem isn't giving the +1 bonus at level 5, and a level 5 or 6 gem increased to level 10 through modifiers is providing a +1 bonus to supported skills instead of +2.