Demon hunters wield weapons specially made to be most effective against demonic energy and thus demons. While hunters call them “blessed”, they weren’t actually blessed by angels but were instead forged out of the crystallized corpses of demons.
Ironically, those weapons are weaker against lower demons, because their power is proportional to the amount of demonic energy they are used against.
Demons can infuse any object with their energy, corrupting it and turning it into a demonic artifact. Those can be used as vessels by demons who can’t or won’t manifest in person on Earth, or as weapons to harness a demon’s power.