User blog comment:Fliu/Chapter 946: Luffy's Next Big Step/@comment-180.191.122.111-20190622004046/@comment-2600:1702:3C50:A6E0:1DFB:234A:DA0F:186E-20190623203437

It would make sense that two defensive techniques would help bolster the defenses, people have been looking forward to seeing CP-0 use their six powers in conjunction with their haki. If Luffy could use iron body then this idea might work. As for haki alone, Luffy should work on not only using small amounts with a big Effect, but making his haki stronger and enabling it to last longer. I assume he should be able to do this through training and experience as with many things. It would also help if he could use gear 4 longer or at least combine gears 2 and 3 again to eliminate the weaknesses of the individual gears. The point being, there are a lot of possibilities for improvement and Luffy might want to consider all of them. That way he has a number of options. Smoker to my knowledge is not an admiral, but he might as well have been at the time due to his intangibility. Now that that advantage is gone, he would need to rely on his skills to fight Luffy when and if they fight again. The Admirals are among the strongest fighters in the world government so they will not be easily bested. Like the Yonko, they symbolize the heights of power in this world. It would not surprise me to find that the other admirals have methods to keep people with haki from fighting them evenly as well. Still your example is a good one especially since I believe despite some others not doing so that Luffy will fight Akainu again.