To buy and sell items in Tribes of Midgard, you will need to locate two NPC merchants called Merchants and Sorcerer.
The Merchants can be found via a gold bag icon on both the mini and world map, and the merchant NPCs can be used to sell all sorts of items you can gather in the game in exchange for souls. We highly recommend using this NPC, as certain items like the golden egg rune can be sold for 200 souls.
However, if you want to buy certain items, you will need to find the Sorcerer instead. You can find the Sorcerer via a T-shaped rune icon on both the mini and world map, and the Sorcerer can be used to buy all sorts of rare items in the game for souls.
As a side note, You can also check the map legend to the right of your screen to help you locate both NPCs on the world map.
Also depending on the location the Sorcerer is in, they will sell items that you can obtain from various sources in that region, so if it's the land of pools, you can buy mushroom bolts, linnorm spikes and more.
That being said, both NPCs can be very useful to find if you have either an overabundance of some items or want a quick way to get certain rare items in the game. That being said, once you locate both merchants, we highly recommend keeping track so you can use both of their services throughout your match session.
Check out some more Tribes of Midgard guides at Pro Game Guides!