Starred Ninjutsu/Omnyo defence reduction Bonuses can be forged?

Hello fellow Nioh warriors!

I was wondering if the special bonuses like "Reduce Defense with Ninjutsu" or similar Omnyo effects can be forged on gear, or if they can only be acquired in the Abyss. I've been trying to forge some Hayabusa arm armor with these specific bonuses, but I keep getting less useful ones, like "Ninjutsu Damage with Max HP."

Any advice or help would be much appreciated! Thanks in advance!