In Greek mythology, Hades' magic cap or helmet renders its wearer invisible. The most famous user of this piece of equipment is Hades' nephew, the hero Perseus, while on his mission to slay the Gorgon Medusa.
For the mission, Perseus was outfitted with some other magical apparel, including a sword (or sickle, or sickle-shaped sword), a pair of winged sandals, and a bag in which to carry Medusa's severed head. Together with these he is sometimes said to have had also a polished shield to use as a mirror in order for him to be able to look at Medusa's reflection, which was harmless, and thus see her without the danger of direct eye contact.
I imagine that an invisibility cap is quite useless if it doesn't also hide the clothes and shoes that one is wearing in addition to the rest of him. So presumably Perseus' clothes (and bag and winged sandals?) went invisible when he wore Hades' cap. But what about his sword/sickle, or something as big as I imagine his shield was?
And if the shield did become invisible because he was carrying it, how could he use it? Could he himself see it (and the reflection in it) even though it was invisible? And is this because he too was invsible?
I suppose it would be like a bubble of invisibility surrounding Perseus so that he could still see (all of?) himself and all his stuff but no one else could. The exception to this is perhaps Athena, who Apollodorus (in Bibliotheca 2.36-42) says guided Perseus' hand to strike the killing blow against Medusa while he was using the polished shield's reflection. The same account also seems to describe Perseus wearing the invisibility cap the entire time from before until after his encounter with the three Gorgons.
Are these the best clues as to whether everything borne upon one's person becomes invisible to others while wearing the "cap of darkness," or is there a clearer mention of this anywhere else?