I don't think its about power, i think its about the symbolism. If sanji gets the DF, i see oda giving him an eat it or lose it choice. I think he eats it and tells luffy we won't leave you to get hurt like that ever again! I think this will be a nice chance for Oda to explore the crews feels about not being their for luffy 2 years ago and basically, we will do what it takes to protect our captain. Whether its from battle or emotional pain.