I've been out of practice with my medieval arms for quite a while now on account of a "stress injury," which has improved a bit, but still will persist as a detriment. Allow me to explain:
(1.) Don't get mad. Ever. Or something like that.
(2.) A man in armor was no joke, and punching him was likely a good way of hurting yourself in a last-ditch defensive situation.
(3.) One does not necessarily feel extreme amounts of pain upon breaking or fracturing a bone.
The injury in question was brought about by stress in the workplace and less-than-ideal conditions (also terrible decisions). I had a worker shoot himself on accident with a nail gun - the first thing I sought to do was to get access to the medical cabinet so that we could clean anything up that could be cleaned up with the supplies on hand. The injury was not serious, but I care about our people, so I was trying to do what I could. I requested that the cabinet be opened - it's normally locked so it's not pilfered, which has sadly been a problem in the past - the first thing I'm asked is, "why do we have to open the medical cabinet?" After telling just about every new employee I've inboarded about that damned cabinet and the trouble of getting it open, I just snapped and set about to hit something I felt might give, which ended up being the back side of a locker (we make lockers, by the way). Well, it didn't give, but my hand certainly did, with the right-hand metacarpal bone of the little finger fracturing (though I did not know that at the time). Pain was not significant, the injury was left untended until it was too late to set without surgery, and the bone healed incorrectly.
Introduction over, I can move on towards the main point. I've found that a longsword is not difficult to control post-injury so long as both hands remain on the weapon. The problem is in handling a single-handed arming sword - mine happens to be an Arms & Armor Grunwald. Because the little finger metacarpus is now arched upwards and the grip of the sword in question tapers inward toward the pommel, edge alignment control is now quite tricky. On the bright side, I think this issue could be resolved with a new handle design which might flare and swell in the area of the break - I will in fact have to attempt this when I get around to building my Type XIV from an Albion moat blade. I may be able to adapt to using the sword again with a decent amount of precision in the future, but there's going to be a bit of time between then-and-now it that's the case.
In terms of reality and gameplay you end up with a few items to consider from this event. Fractures and breaks may not be immediately debilitating, but they may have long-term effects on the individual. Arms may become difficult to use, or specifically-made arms may be required for proficiency to be maintained. Regardless of the case, I've not seen too many examples of this sort of (permanent) thing in the games I've played so far, but from personal experience, I'm inclined to feel they should. It certainly makes things a little more difficult, though perhaps more interesting as well.