The new event for the 72 atk sword is out. This event seems nice so far. Each exploration gives around 12-16 ore, so you can easily farm enough materials for multiple blades without much grind. Be aware though, the pro dungeon is for endgame characters, so bring your A team. You have to fight a gauntlet of three bosses in a row at the end, and they're rough. Some random tips:
Bring a tent, and maybe some ethers.
Having a unit with an escape skill helps since the special materials are from gathering points and the trash mobs are very resilient, so it's usually better to just run from trash.
First boss is aquatic, last two are humanoid, so killer passives from materia or innates are great if you have access.
Last boss does blind and paralyze, so plan accordingly.
Earth resistance (gaia gear, golem esper, barstonra) helps on second boss, his AoE quake hurts.
Bring a whale friend, it helps... a lot.
I recorded my first clear of the end bosses, which you can watch to maybe help prepare your team so you don't blow 16 energy. Keep in mind it was my first run, so my team wasn't optimized for these fights, especially that last boss with his annoying status effects.
Final bosses video
I had planned to make a single sword, but since it's only like 5 runs per sword, I think I'll craft at least two. Once you farm enough of the special ore from the pro dungeon, don't forget you can go back to the previous dungeon and farm wood/ore, since it drops like water during this event.