For a real look at the situation, look at the police force of any country, not the military. Police face real, dangerous conflicts all the time. There are plenty of policewomen out on the streets. They're not all guns either, any real police officer needs to be prepared to go into a conflict unarmed. I've heard stories of a 40+ year old homeless, undernourished (but mentally ill) woman throwing a trained police officer twice her size and biting his face off. I've also heard stories of country girls who can easily lift things their own weight, because they do it every day.
Take a big guy, trained in any martial arts... more so the type which trains people to 'disarm people wielding knives'. Find a female friend, average sized. Give her a marker, pretend it's a knife. Tell her that the big guy is trying to take away and kill someone under her care (like a little brother or son). Half the time, the guy will have marker marks on his throat and face. Give the guy a marker to even things up and she still stands a good chance, because the martial arts conditioning will slow down the trained person.
For the first part: there may be some merit to that observation. I don't know how much, if any, scientific evidence there is to back this up but I've heard it said that a big part of teaching combat technique to women is just teaching them to not hold back when the situation warrants it. It's easy to get handicapped by your own brain telling you "You're not strong enough," "You can't beat this guy," etc. and you end up even less effective than you could've otherwise been. Not that this is a strictly female issue, obviously, I just remember reading somewhere that it's more conditioned into women by society that they're not supposed to be violent etc. etc. so they have a harder time overcoming that hurdle. No idea if it's accurate, but it could be a factor. *shrug*
But the second part...martial arts conditioning slow down
the trained person? Um...I don't think so. Overthinking things slows you down. Martial arts conditioning helps you not overthink things. I sincerely doubt I was an exception to the rule when I got faster
after a few years of martial arts training; I would think that's the normal result.