If you want to speed your way up to G-Rank so you can do the DLC, here are the key-quests.
Guild 1:
Bug Burger
Kecha Konundrum
Tackling a Tetsucabra
The Gypceros Project
Guild 2:
Web Sighting (Urgent)
Royal Assassination
A Ghastly Gift
Zamtrios of the Deep
Nix the Najarala
Guild 3:
Dark Wings, Dark Work (Urgent)
Tigrex Tough Love
Temper Tantrum
Royal Audience
Tuff Turf
The Royal Guard
Advanced: Sand Sailor (Urgent to HR)
Guild 4 HR:
Face Two Face
Purple People Eater
Buffoonish Baboon
Dastardly Duo
Guild 5 HR:
Rathian's Wrath (Urgent)
Writer's Block
The Red Menace
Dread Locked
Temper Tantrum
Advanced: Frenzied Foe
Guild 6 HR:
Ore D'oeuvre (Urgent)
Bring Down the Sky King
Infernal Overlord
Ear Ache
Brimstone and Brachydios
Guild 7 HR:
Advanced: Stop the Wheel (Urgent)
Advanced: Grim Tidings
Advanced: Teostra Tangle
Advanced: Storm Front
Advanced: Fleet Action
Advanced: Speartip Menace (Urgent to G-Rank)
Advanced: Glacial Grinder (Urgent to G-Rank)
Then, I believe you fight your first Tigrex (for the Clockwork Glaive) in Guild 9.
Unfortunately, both the Legend of Zelda and Clockwork Glaive are pretty much vanity weapons. There is very little merit in using them other than having a cool-looking weapon. But, I would totally make that Clockwork Glaive as well, haha.