You make a great point about armor. Pirates are light troops for the most part. Plate was available during the period, but expensive and uncommon. Goddess is the final arbiter of course, but I don't think anything heavier than leather types of armorfor charcters fits the Pirate theme.
As to what character class I will play, I'm kinda torn. between:
Acrobat: Duck and dodge, always on the move. Perfect for those dramatic leaps from the rigging of one ship to another, carrying a grappling hook to secure the two vessels, scrambling up the walls of a fort in the dead of night or under fire. Positive, upbeat personality, something of a party girl, might even dance on tables when the ship is in port.
Sniper: Spooky introverted killer whose smiles seldom reach her eyes. Keeps to herself as much as possible. Impossible to do on ship I know, but when ashore tends to disappear into the background.