Alright, then we agree - all Heroes can use Toughened Leathers.
I've read up on them again, and this is what I've found:
"Special Rule: Toughened leathers work exactly like light armour."
"Scaly Skin: (...) Light armour adds +1 to the save, as does the addition of a shield."
So... If Toughened Leathers work excactly like Light Armour, it should add +1 to the save.