I understand everything now.. Based on the sequence of events that kept bugging me..
I have not had the chance to look at the Japanese raws but i can safely assume that Kizaru is not upon Luffy..
I think that what Luffy is actually implying is not that '' someone '' very powerful is coming, instead that '' something '' very powerful
is coming..
Kizaru's attack to get rid of Sentomaru was so large that it's reaching where the Sunny and the Strawhats are..
So Luffy is signaling his crew to brace for impact cause a powerful AoE blast made of light is coming their way..
What do you think?.. Spot on.. Completely out of my debts..