This again? Why is it that people have no trouble believing that the male human character can hold their own against a larger Qunari or ogre or even dragon, but find it hard to grasp that a female character could hold their own against a male character of their own species?
Size, strength, and weight do offer advantages in unarmed combat. I won't deny that. I also won't deny that men are likely to be larger and somewhat stronger. However, that's where it ends. I'm better with weapons than without, and I know I'm capable of winning grappling matches against guys who are a foot or more taller than me (sidenote: I'm 5'2", not fighting giants). Not all of the time, surely, but a reasonable portion of the time (there are people I know about my own size who I have a much harder time against, for that matter), and I see nothing wrong with assuming that the clearly larger and probably stronger PC is much better at it than I am. I don't even spend as much time working out or practicing as I could, because my job eats in to that potential time. I can't paint while fighting. Someone who is a warrior, who does very little other than fight and that for their life rather than interest or a hobby or even money, does not have that problem. For that matter, I've seen smaller people than I take down larger people.
This isn't even unarmed combat, people. It's all combat with weapons. It is quite easy for smaller people to be strong enough to effectively wield their weapons, which is all that you need to do -- the rest of it is skill, speed, and experience. If you are strong enough to get your weapon to do what it needs to do (and all weapons are designed to be good at this, be it a sword or an axe or a hammer), you are strong enough. Weapon weights in games, additionally, are typically quite out of whack with reality. I don't recall what they are in Dragon Age, but realistically a two-handed sword would be from 2-3.5 pounds.
As for height, different heights simply have different advantages. Generally speaking, taller people are at an advantage at further distances, and shorter people are at an advantage closer in. There is nothing unbelievable about a shorter person killing a taller person, particularly when both are armed. It has happened many a time. Does anyone seriously think that, throughout all combats in history, the larger (or even larger and physically stronger) people always won? That the shorter people may or may not be female changes nothing, because even with the (much slighter than people like to make it out to be) differences in body strength, it's easy to be strong enough to effectively wield a sword.
And different animations? Dude, no. There's no reason for that. The wonky walking/idling animations for female characters are bad enough. We need less of that, not more of it.
Now, I am often annoyed by how male characters end up looking strong but female characters don't. That's mostly a different issue, but I suspect more realistic strong physiques on female characters would cut back a bit on people complaining about them not looking like they can wield their weapons. I'm all for female characters looking stronger. That would be great.
Oh, and this is all even leaving aside that there as so many unrealistic things about combat in DA II that I wonder why anybody would jump to "possibly unrealistic that smaller people/women can hold their own against larger people/men in combat!" as their complaint of choice.
The martial arts thing gets thrown around a lot and looks cool in movies/olimpics, but reality is pretty different.
There is a reason why the 101 of proper personal defense is "if you can, flee".
Yeah, the reason is that if you get into a real fight, one or both of the people involved are going to end up injured. At least one will wind up severely injured if it's an all-out fight, and potentially crippled or dead. It's not that one has no chance against larger or better armed opponents (discounting the possibility of a gun) -- it's that it is far better to simply avoid the risk that the odds won't be in your favour or you'll slip up, avoid the wounds you'll incur even if you win, and avoid the jail time you may incur if you win.
And yes, many martial arts moves are flashy and take long enough that they don't get used in actual street fights, but there are also many martial arts techniques that do work well in such situations. You just don't tend to see them in films or games as much, because they are less showy.