Tian Xuesong and his group initially thought that the potions Wang Tao had were Rejuvenation Potions, which, although quite magical, obviously weren't enough to trade for military arms, right?
However, when Wang Tao introduced the potions he had, revealing they were Strength Potions and Defense Potions, they were all instantly amazed.
Cheng Yiyi had tested these potions because Wang Tao had also sold some to her. So, she helped Wang Tao prove the potions were real.
With Cheng Yiyi's endorsement, the leaders of the three major legions immediately expressed their need for them.
Since they wanted them, that made things easy.
Wang Tao called Lan Yulian over to discuss the prices with them, while Wang Tao himself stepped out for a while.