By the time a woman notices you're left-handed, given that she's around for that long, you're well beyond being judged for anything that superficial and she won't care.
You can always turn it into a disadvantage though by being hung up on it and thinking it's somehow bad, women will for sure reflect what you think of yourself. This is why insecurities are so detrimental, if you don't even like yourself then how could they?
I certainly have a few imperfections, I have a choice whether I want to let that define me or not. I can choose to reject myself or not. Obviously I chose to accept myself as I am. If I ever come across a woman who just has to point any of it out in a negative light, which has never happened, then she is just a rude cvnt and that's as far as I'm concerned uglier than any of my own imperfections. Not the type of women I want to associate myself with.