Today, I took the special event for a run, and was delighted to not only re-obtain the Gjallerhorn (I missed this launcher so much), but to discover Halo weapons to use. The Halo 1 Magnum pistol is an exotic sidearm called the Forerunner, the Battle Rifle is a legendary pulse rifle called the BxR-55 Battler, half the Energy Sword is the Half Truths legendary sword, and the first non-exotic trace rifle Retraced Path is based on the Focus Rifle.

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There's also a Void version of the Beam Blade called "The Other Half". And you can get Eager Edge with both of them.