How do you folks go ahead with learning new weapons once you are in Master rank?

So I'm currently at MR5, I think I'm nearing the end for story content. Obviously I learned there's stuff to do after it. But I also want to branch out and learn a new weapon.

I played hub quests with dual blades and then created a new save to learn the bow. But I don't want to do that again as I have a lot of stuff on this save and want to continue on it. So is there any any specific content you can use to learn a new weapon? Or how to go about it.

Also suggest something after dual blades and bow would you? I'm feeling something melee and heavy but don't know which one to choose. Thanks.

Edit : Thanks a lot for all your replies. I'll keep the MR gear and forge a hr weapon and then continue going through the monster roster to upgrade the weapons and decos.

I've chosen a great sword next because it has the most change of pace coming from Dual blades and Bow. Thanks for all the help people. Peace and happy hunting.