Lord Shaxx is the vendor in Destiny 2 that deals with Crucible rep. He is located at the Farm once you unlock PvP and at the Tower once you complete the game.
When trying to grind out Reputation for Crucible Engrams it is wise to obtain and use a Ghost that will reward you with additional Crucible Tokens upon completion of Crucible Matches.
Lord Shaxx accepts Crucible Tokens in exchange for reputation points. 20 Tokens will be required for a full level of Reputation. Once you have handed in 20 tokens you can collect your Faction Reward which will show in his menu as a Legendary Engram. You can get one or more of the following items from each engram you collect from Lord Shaxx:
- Faction Helmet (Class Specific)
- Faction Gauntlets (Class Specific)
- Faction Chest Armor (Class Specific)
- Faction Leg Armor (Class Specific)
- Faction Class Item (Class Specific)
- Crucible Glory Shader
- Faction Auto Rifle: Martyr’s Make
- Faction Fusion Rifle: Critical Sass
- Faction Grenade Launcher: Play of the Game
- Faction Scout Rifle: Does Not Compute
- Faction Shotgun: Retrofuturist
- Faction Sniper Rifle: Gentleman Vagabond
- Faction Sword: Steel Sybil Z-14
- Legendary Shards
- Misc armor pieces and weapons in a shifting lootpool
You can check the exact stats of the items or what is currently in the shifting lootpool by pressing or on the Faction Reward Engram while speaking to Shaxx.