What do you guys think about Luffy learning a secondary fighting style??
Being as though we see that Haoushoku Haki isn't the quick fix to everything.
For example, even with Haoushoku Haki, if Luffy fights Akainu... he'll still melt if he touches him barehanded, even if the punch manages to hurt Akainu. And Haoushoku Haki isn't going to stop him being poisoned if he Megallen again either. Haki makes it possible to hurt Devil Fruit users, but it doesn't cancels out or nullify their ability, just makes it possible to hurt them.
Like we've seen, Whitebeard's Haoushoku Haki and his powerful Gura Gura fruit would be useless against Kizaru who is Light. Which is the only time we Whitebeard attack Kizaru is with his Bisento, other that, Marco (a Haki-user) is the only one to fight Kizaru throughout the War because of their respective ability. I can go on and on giving more detailed examples of why I think Luffy will need a weapon/secondary fighting style. But I'll just wait and see what you guys think.