The best & easiest location is the Quartermaster’s Stores shop located in the Tyras Camp, accessible via Port Tyras.
Quartermaster’s Stores
The Quartermaster’s Stores shop is run by the Quartermaster, and is located in the Tyras Camp in Isafdar. The shop stocks 7 adamant halberds priced at 8,320 gp each. Below is a screenshot of what the shop looks like: This shop actually stocks every kind of halberd from bronze to dragon, as well as other handy items you might need, such as:
Pots Jugs Empty jug packs Shears Tinderboxes Bread
You can access this shop by traveling to Port Tyras via the Charter Ship from any of the following locations:
Catherby Brimhaven Port Khazard Corsair Cove Port Phasmatys Musa Point Port Sarim Shipyard Mos Le’Harmless Prifddinas
The cost of traveling depends on the distance of the journey. So the cheapest ports to travel from are Prifddinas, Brimhaven, Port Khazard, Corsair Cove, or Catherby. Pictured above: The charter travel map with destinations
Shopping at Iorwerth’s Arms
The Iorwerth’s Arms shop is run by Celyn, and is located just south of the center of Prifddinas. It stocks 7 adamant halberds selling at 9,600 gp each. And this also has a few other weapons you can pick up as well:
Adamant daggers Rune daggers Dragon daggers Adamant scimitars Rune scimitars Rune halberds And dragon halberds
To access this shop (and the city of Prifddinas in general), you need to have completed the “Song of the Elves” quest. This quest has a long list of requirements, including several level 70 skills: Agility, Construction, Farming, Herblore, Hunter, Mining, Smithing, and Woodcutting. All of those skills are not boostable for the quest. But you’ll also need to complete several other long difficult quests too, such as Mourning’s End Part II. Due to the higher requirements to access Iorwerth’s Arms, plus the fact they charge higher prices, it’s better for you to go to the Quartermaster’s Stores shop on Port Tyras instead.
Why Would You Want Adamant Halberds?
The halberd is definitely a niche weapon in Old School RuneScape, since it’s one of the few weapons that allows you to safespot while using melee instead of ranged or magic. Pictured above: Player using an adamant halberd to kill a blue dragon from a distance Furthermore, an adamant halberd is required for a medium clue scroll step where you’re required to clap and spin outside the Seers’ Village Courthouse – all while wearing a mystic robe bottom, a diamond ring, and wielding an adamant halberd.
Trivia: Attack AND Strength
Halberds have requirements for attack and strength levels before you can wield them. The adamant halberd requires 30 Attack and 15 Strength.