@daywithoutgames It really isn't that different from a smallsword, which only rarely broke the 1.5lb/680g mark and probably 2/3 of that weight is concentrated in the hilt; it's not that different from swinging around a branch about as thick as your thumb with maybe a 1lb/450g dumbbell in your hand; if she's incapable of
that, I'd be more worried about the fact that her muscles have clearly atrophied than I would about her swinging a sword around.
As for the fire mages, it may just be that silver is considered the only
easy method of killing them; I simply
refuse to believe that every single creature caught in either of the two humongous blasts we saw somehow managed to escape unharmed because they can "only" be killed with silver. That's just atrocious writing. It could be that fire magic only has a 20-25% kill rate, so it'd be a choice of 4-5 fire spells versus 1 swipe of a silver sword. To any kind of tactician, that would be enough to write off anything but silver. Your mages would simply be better spent as crowd control, which is probably why they still have them.
Of course, while typing this, I hit upon the biggest issue I have with these creatures: how does the silver actually kill them? Since they're classified as undead and the silver is "holy silver", does it just act like a magical kill switch when it hits them? If that's the case, the people of that world
deserve to be genocided, because their tactics are so laughably, horrifyingly inefficient, I'd be half tempted to annihilate them all just to erase the embarrassment. You have 3/4 of your female population sacrifice their reproductive ability in order to protect the fourth; if the silver is, indeed, a magical kill switch, I'd say that each swordsman could probably kill, on the extremely optimistic end, maybe 100 creatures before becoming exhausted. Since these things seem to come in waves of thousands, you'd need, minimum, about 100+ swordsmen just to break even and that's assuming none of them were incapacitated or killed.
There's a reason the sword was a secondary or even tertiary weapon on the battlefield while the spear was king: it was cheaper to make, easier to learn, and could be used in formation. Why not use all that silver you're wasting on swords to make even more spearheads? A decent sized spearhead weighs about 8oz/227g, while an arming sword blade weighs about three times that, and a longsword blade about four times a spearhead; in other words, that's 3-4 spearheads you could make for one sword. More if you made the spearhead smaller, since it doesn't need to be that big to be effective. You could turn all of those swordsmen and shieldbearers into spearmen equipped with a spear and a scutum and form them up phalanx style with mages in the center for support and crowd control and be far better off than these idiots are.
Even better yet, use all that silver to forge arrowheads (which can be about 1oz/28g or less) and you could easily get tens, even hundreds, of thousands of them; turn the majority of your people into archers with a small contingent to become white mages for healing and black mages to keep the creatures from grouping too much at any one point of the barrier and rain death on them from the safety of the walls. Retrieve arrows in between waves, rinse and repeat. These things are naked and dumber than beasts, so the only reason the people of this world are in any danger is because they have to get into close combat with the things to stop them from destroying their barriers.