Which came first for you, your grab or your character?
The reason I ask is that I am at an impasse. I think I have a vague idea of what I want my character to be, but I have no idea if that type of character existed or if the type of garb I picture him in would be H.A. So would it be best to do research first and figure out if/when/where it existed and go from there or just build the costume more or less and then figure it out from there?
well, my character isn't HA, so it was easier for me to get the garb first and make up a character that suited it. I think that if you're going for an HA character, you might want to decide who it is first, and then you'll have an easier time of deciding what to wear...
Hot Weather in Texas = Spanish garb designed for similar climate.
Spanish garb = Spanish persona.
(Though His Lordship enjoys calling himself an Overdressed Spanish Peacock just a little too much)
My character sprung from the nickname that I had acquired over time as a computer geek..."wizard." My wife has called me "Merlin" for a couple decades, I suppose. I'm not H.A., being a fantasy character, but that does leave me a little more wiggle room in my costume.
The idea for my garb came years before I worked it up, before I became a wizard I garbed as a knight but clanking around in my armor was getting to be too much work. I say that if your inspired to a particular persona, run with it. If it doesn't work historically then you may want to consider using it for fantasy faire or conventions instead of renfaires. Though I have run up on people in all types of garb and ilk at renfests, a couple of years back I met Abraham Lincoln, stove pipe hat and all at a faire.