You will encounter 7 trainers during the game. All trainers can train you up to level 8.
Hunter can teach you bows, thrown weapons and foraging. She can be found in "Fletcher's Grove", hidden deep in Wolfenwood. From Everdale, head west into Wolfenwood and follow the main road. You should notice a bucket at coordinates X=63 and Y=99. From the bucket, travel northwest into the trees and you will find the grove.
There are 5 trainers in Port Kuudad. In the middle of Port Kuudad where the city marker is, you will find Sonya who has returned from the first game. She once again teaches swords, cleaving and bludgeoning weapons in her new establishment, "Sonya's House of Pain II".
Luci teaches elemental and divination magick in her shop, "The Darkest Arts Magick Supplies", which is directly north of the city marker.
Ned can teach you cartography in the building, "Mistfell Port Authority", which is southeast of the city marker.
Becka is just southwest of Ned in her own shop, "Excelsior Elixirs and Alchemy Supplies" where she teaches Alchemy.
The last trainer in Port Kuudad is underneath the city in Thieves' Arcadia. To access this area you must solve the four chest puzzle in the sewers of Port Kuudad. Zeblin is in his lair at coordinates X=90 and Y=157. He teaches hide in shadows, move silenty and pick locks. Zeblin will only train you if you have the quest: "To Hunt an Assassin", a quest you can accept when you pick up the Soulpiercer arrow from the corpse of Darus. In dialogue with Zeblin, you must abandon this quest or he will not train you.