Is “The devilish king and his three axe moves” true?

In the Romance of the Sui and Tang Dynasties, Cheng Yaojin wields a large axe and knows only 'three axe moves', and once called himself the 'Devilish King'. However, the Old Book of Tang, Biographies of Yuchi Jingde, Qin Shubao, and Cheng Zhijie records that Cheng Zhijie (originally named Cheng Yaojin) was in fact 'brave and fierce from youth, skilled in the use of the horse lance', not an axe. In official history, there is absolutely no absurd deed of the 'Devilish King'; he was actually a valiant general who rendered outstanding military service in the founding of the Tang Dynasty.