Do you live on Oahu? Even if they allow scissors aboard the ship, I doubt the airlines will.
There's no self service laundrys aboard th ePride of Aloha or Pride of America. I expect the Pride of Hawaii does. Ships with self service laundrys usually have irons at the self sevice laundrys. There's usually significantly more fire suppression capability at the self service laundrys than in your cabin.
They will not issue you an iron for your cabin. Irons are considered fire hazards by many; some cruise lines will not allow you to bring them aboard. Although the NCL web site fails to mention them specifically.
I recommend taking a travel steamer instead of an iron aboard.
There are hair dryers in every cabin aboard every NCL ship.