I'm not as interested in a combat rework as much as I am interested in the rework of mechanics surrounding it.
I feel Vintage Story fails to inform the player about certain mechanics sufficiently, or fails to deliver these mechanics in ways that are fun and rewarding to engage with, as opposed to simply being friction points that detract from gameplay with little potential gain.
Temporal Storms are unrewarding and frustrating as I've had multiple experiences with a strong enemy spawning right next to me, and oneshotting me in the second temporal storm of the year, and even if I struggle to kill things, I generally don't get more than perhaps a rusty gear, and a few bits of flax string. They interrupt whatever my plans were, punish me for straying from my base and going on excursions, and are unrewarding for the risk they carry.
Temporal Storms just need a rework in general. I can live with having to trek back home when I'm warned of one incoming, you're given plenty of warning for that. But enemies spawning on top of me sucks, and even with the armour I can get on year one, it's not going to help when a Corrupt Drifter spawns in my house on top of me, and going outside means I face about 5 other enemies at once in the dark. Even surviving all this isn't particularly worthwhile due to the best case of loot being a couple of gears, and possibly a temporal gear if you're quite lucky (although it serves little purpose early on anyway).
Sanity can designate a surface area as unstable very arbitrarily, which functions as a "hey this area is cursed and if you build here you'll lose sanity over time" but has no purpose - this area isn't any more rewarding than others due to the risk, it's just a random area selected to be uninhabitable.
Sanity shouldn't make random patches of low sanity areas, it adds absolutely nothing to the gameplay, and is just an invisible punishment towards newer players learning the mechanics, and players who get bad luck with really pretty areas they want to settle in. Beyond that sanity is overall a feature without much content at all anyway.
Damage tiers are explained as "low tier armour is less effective against high tier damage", and there's no mention ingame as far as I know of the fact that enemies can hit different part of your hitboxes. So if you have full Steel Plate armour on your chest and legs, a bear hitting you in the head will deal full damage and possibly kill you from near full health. This is such an important mechanic that isn't explained, and it makes Improvised Armour potentially not protect a new player at all, leaving them confused as to why their armour didn't even take damage when they got attacked.
I feel that the guidebook could do a better job of explaining armour only protecting one part of you, whereas in virtually all other games, including ones in the same genre, armour tends to be a general 'take less damage' instead of a 'take less damage ONLY if hit here'. I know it makes sense if you think with real world logic, but this is a videogame.