Glorious, glorious Kamigawa block! Home of weird cards that have very specific uses in which they excel, but were completely useless at the time! I love it so.
So I wanted to use the prompt to do a straw hat. Then I remembered this hat, and I did a research. I found it fascinating, and looked at how to translate what it was and what it represented as a card design. I remembered that there are strange card interactions that can cause a permanent to have no name, so it is permissable by the rules. Being unblocked is also accurate, but using that to go in to do a murderin' would have been rather... bad. So, 0 power. But that doesn't stop you doing a mischief during combat... or just giving them a sword.
Mana cost and equip costs are based on similar cards, equips that grant unblockable but with downside. Art wasn't hard to find. Throw in some Kamigawa-themed flavour text, and job done.