When you reach Chapter XI Halflings, one of the first technologies you will unlock is "Improved Trader", which allows you to upgrade to the Trader. This adds an 'Upgrade' tab which allows you to upgrade the Trader to level 2.
Upgrading the Trader will not affect its current functionality but will add a new tab with the title 'Collect'.
In the 'Collect' tab, the Trader will auto-produce a new permanent resource, Divine Seeds. The resource works like Mana, including production and early collect, display in the HUD, decay etc. In addition, there is a Collection Bonus. Every time the player collects Divine Seeds from the Trader, he will get an additional amount of Seeds, according to his combined AW levels.