The drawback of this divine tool was that while it certainly could brand abilities, with each of its pages capable of doing so, the abilities it branded could only be executed using power of the same level. In other words, if you branded an ability of the Demon King level, you would need the Bloodline Power of the Demon King Level to activate it. Comparatively speaking, its functionality was ample, but it didn't significantly enhance combat power. Moreover, the power of the activated branded abilities was only eighty percent as potent as the original version.
Thus, it was indeed a divine tool, but it couldn't be considered a particularly powerful one.
The reason Tang San chose it was because of its composition; such branding capabilities were quite rare, and most importantly, its material held great potential for development.