Upon return, Wilder Briggs was shocked by Lucius's transformation in the past few weeks. Not only had he grown and become so good-looking one would mistake him for a flawless sculpture, but his presence had also changed.
After interrogating Lucius, he learns about Anansi's blessings, which makes him become this. The revelation shocked Wilder, but he had no choice but to believe Lucius.
He also noted that Lucius's Hand of God ability had reached its peak and was just a step away from evolution. Lucius was at the point where he could undergo the Biogenic process.
The current Lucius now was strong enough to defeat a B-rated guardian, according to Wilder's speculations. In his opinion, while Lucius was at the stage where he could undergo the process, it was not yet time.
The body gains strength when put under stress. The fact that Lucius gained this much power without his body going through the natural process may be counterproductive.