Far as I can tell, flint hatchet. Seems like a tier is missing. There are a BUNCH of high tier axes. But none say “harvest damage”. They’re all melee weapons.
Best piercing weapon
Morningstar, or stinger lance. Stinger lance has same base piercing damage as a chitin spear, but does poison damage too (10-12) along side the 20-28 piercing. Stinger lance is also the first poison weapon I’ve actually seen place a DOT on enemies. About 3 pts per tick. Nothing game changing. By the time you can apply the DOT, you’re already in melee combat. I would say the DOTS all added up were the equivalent of 1 or 2 extra hits with the spear, while fighting a roach in the graylands (the HUGE ones).
Best edged damage weapon
For me, the iron sword. Does a cool two hit combo. You have to learn to time your attacks so the second strike will actually hit the enemy. Enemies that move around a lot can dance out of the way of the 2nd strike, and you swing through nothing.
I prefer swords to the axes. The swords seem faster (animation wise).
The iron scythe is nice too, does a forward chop, and then a 360 spin attack. The spin attack strangely doesn’t seem to hit multiple targets. I was testing it on the graylands flies (which attack in packs), and I could slice and dice one at a time. But seemed like just one each attack. Might be a bug.
The scythe is one of the FEW things in game with a crit chance higher then 5% (that being 10%). Very hard to tell if that was really making a difference.