People seem to disagree, but if you're one of the players that likes taking it slow and building/maxing gear, like me, then fully upgraded bronze will let you glide through the swamp with ease. No poison resist needed for this. All you need to do is parry Draugr and archers, avoid everything else, especially aboms (though they are easily doable if you're not mobbed by ads and can parry, just probs not worth it for now.) Make sure you have decent food. For me, cooked Deer, Boar and Neck was good enough to loot a few crypts, though better stuff is nice. I am replaying Valheim after a long time away and have just cleared a swamp of around 9 crypts and now have more iron than I know what to do with. Just make sure you create a base in the biome across so you can smith there and portal to your main base if needed.

First thing I made was full iron armour to get even tankier, now all I have to worry about is 2 star draugr (and then only if I fluff a parry or my stam management) everything else is easy when I am fully fed.