The Regalia Bloom bloodline allowed the user to take control of all kinds of energy within a certain zone, with only physical strength and stamina as the determining factors for how much energy the user could manipulate. The energy could be used by channeling it into any weapon or item as the medium for energy transfer. Though there were a few limitations and price, such as the endless beautification of the bloodline holder, and the user's ability to transfer the energy fast enough, theoretically such a bloodline would make one nigh invincible.
If Lex had this bloodline, along with his incredible reflexes and abilities, he most likely wouldn't even get a chance to use that incredible defense of his. Just the fact that, as a Qi training cultivator Gerard was able to combat a Nascent level cultivator should be a clear indicator for how powerful and deadly this bloodline was.