Like the arena's class-specific armor sets, obtaining these weapon rewards will require a high level of skill, teamwork, and dedication. The might of these weapons will make you that much more formidable in future battles - as well as serving as an eye-catching trophy of your arena victories.
Area 52 in Netherstorm is where you can find these rewards, offered by a goblin by the name of Vixton Pinchwhistle. He can be found in a hut in the north part of the town, near the inn - look for the two ogre bodyguards standing outside.

Bone Wastes Rewards
Thrallmar

Gladiator's Greatsword3750 Gladiator's Decapitator3750
Gladiator's Bonegrinder3750 Gladiator's Painsaw3750
Gladiator's Maul3750 Gladiator's Heavy Crossbow3750
Gladiator's Slicer2625 Gladiator's Quickblade1125
Gladiator's Cleaver2625 Gladiator's Hacker1125
Gladiator's Pummeler2625 Gladiator's Bonecracker1125
Gladiator's Right Ripper2625 Gladiator's Left Ripper1125
Gladiator's Shanker2625 Gladiator's Shiv1125
Gladiator's Shield Wall1875 Gladiator's War Edge1000
Gladiator's War Staff3750 Gladiator's Spellblade3150
Touch of Defeat1000 Gladiator's Endgame1125
Idol of Tenacity1000 Libram of Justice1000
Totem of the Third Wind1000