Lefim moves his hand amazed by the sting he feels, looks at his disciple and sees Alex is still ready to go again even though the punch he just gave him was strong enough to hurt a peak level mana gathering cultivator.
It seems the decision to temper your body with lighting source, was a right choice to make, using the lighting to quickly evade form my eyes was a good thing, but what are you going to do if someone like me who does not need you his eyes in battle, figure out that you are using lighting to move quickly into that person blind spot, they could easily lead you into a trap and kill you and then will be in trouble then said Lefim.
Alex understanding this thanks his master for the advice, lighting source is a blue in color liquid that is a condensed form of lighting which was created by the rune and formation of Lefim.