the ghoul mask is the only one i know of. it can help you bypass all types of ghouls except for normal ones. to get it you have to go to tenpenny tower accept the job to kill roy phillips(normal ghoul) and take the ghoul mask. it will be easier to help him. if you do he will give you the mask. if you go through the tunnels to find him, which is the only way, you will fight feral ghouls. you also have the option to kill everyone in tenpenny tower, then roy will give you the mask.