Um, I think this sentence is from a animation or game~ “战神一号" & "战皇机甲" may be 2 different robots. ”便宜" - "Pian2 Yi2" - means "cheap" or "advantage" or "profit" ”便宜" - "Bian4 Yi2" - means "convenience" In this sentence, is the meaning of "advantage". That 2 robots' battle effectiveness are almost the same~

“占便宜” 指的是 take advantage of ... 不要把车借给他们，他们在占你便宜！Don't lend them the car - they're taking advantage of you! 但面对这战神一号，战皇机甲却一点便宜也没占到。 战皇机甲didn't take any advantage of 战神一号 when they met.

这个问题很有意思！ 这里的“ 便宜 ”不是形容词，不是“ 价钱低、不贵 ”的意思，而是名词，是利益、好处或优势的意思。 在这里是说战皇的威力比起战神一号并没有多少优势，战皇想打败战神一号是很困难的事。