There are Investments details in the game as follows: some People need money to advance in level (knight online gold), as they level they make money also. What you are getting at is that you can essentially make money by capitalizing on this idea. You usually invest in Mages or Knights since their gain is usually higher than that of a Knight Paladin.
Let us suggest you loan a sorcerer 20 backpacks of man fluids, you could make a deal like you get all the loot he collects as payment which depending on the skill (knight gold) of the Sorcerer should bring you in a little award. The downside is the reward, which might be small, but if you think about it and you can increase the amount loaned as time progresses to receive larger rewards and it's free money. Thanks for your reading and welcome to come again!