It is a magical bug, that will allow the owner to hear what is said in the immediate vicinity of the “bug.”
Once two or more matching helms are found and worn, they enable the individuals to communicate like they were standing next to each other. The helms transmit all sounds including the surrounding noise and at the same volume as the original.
Itching dust makes someone or something itch. It is very distracting and only gets worse until the dust wears out or an antidote is applied.
Wearer of this shirt can walk unnoticed into almost any even/gathering/bank and perform just about any action without being noticed. Only extremely out-of-place action will get the wearer noticed at all.
The PCs encounter a strange set of artistic drawings done on the ground as they pass through a city. It has been done in chalks and no one saw who did it. Wizards might recognize the writing within the colored square as an obscure and dead language with a message stating that a prominent wizard and a retired bard have discovered how to populate Arcadia with the spirits of the dead!
Is it a local hoax, or are the PCs crossing the path of a very deranged and possibly dangerous mage?