I'm going to second the praise for the knife. I've gone through the entire game now (with the exception of the queen), and there it nothing you can't defeat with a knife (and some sort of ranged weapon, of course).

That said, my preferred weapon is still the sword. Mowing down a lox with a knife before it even gets a chance to attack is awesome, but it falls short against multiple targets compared to the sword.

I'm not a blunt weapon fan, but the frostner is a great weapon.

IMO, type damage type makes no difference. Don't concern yourself with trolls and skeletons, and blobs, and stone golem, etc. You can either kill those with anything, or they're too slow be a threat. You can carry a mace for a stone golem, but you can also kill them with a knife if you want to. It just take a bit more time.

None of the mobs that are a real threat are weak or resistant to anything, with the exception of the mistland mobs, which are resistant to all normal damage equally.

I've never used a spear, but I've seem some good things about them.

IMO, the weapons are pretty well balanced in Valheim, so pick what you like and use it. In the long run, you're personally going to fight better if you practice primarily on a single weapon type, and your character skill will increase faster. You also save the inventory space and cost of building multiple weapons.