Mistwalker is the upgraded frostner though its a sword. But the mistlands have provided a host of excellent weapons that include a new spear, a new atgier, crossbow, dual knives, 2h sword, 2h hammer, polearm, axe.... and of those several stand out as worth any amount of effort to produce.

the sword is just good all around, frost slow is powerful, damage is solid.
the xbow hits really, really hard. As in just 3 from behind shots for a lox.
the atgier has aoe and stun. Its probably #1 in the game because stunlock, for general purpose combat and specifically being hunted, fuling groups/towns, ice caves/mines, and other crowded areas.

here is my 2 cents: pierce damage is highly resisted by many enemy to counter the overpoweredness of bows. That makes the spear, atgeir, and even the crossbow weaker than they should be. They are still fine weapons, but the lack of resists to slash make the sword, 2h sword stronger than their counterparts. For that reason, and the frost debuff, I use mistwalker almost exclusively now.

I am ignoring the staves here. There are only 2, and they are different enough that both are simply best in class for their type due to what they are. They are arguably the best ranged weapons in the game, but you do have to change your diet and accomodate them if you want to use them. The aim on the frost staff is abysmal. The ease of use of the fire staff is outstanding, if you miss, you need to get your vision checked.

notes: the grind for the new weapons is SMALL once you have the CRAFTING STATIONS. The grind for the crafting stations is RNG driven but it can be a bit rough/excessive if your luck is poor.
-> You can beat anything in the game with draghr fang bow and a variety of arrows (there are new arrows too but you need the craft station), if you don't mind long, long fights.