Commander Zavala is the vendor in Destiny 2 that deals with Vanguard Tactician rep. He is located at the Farm once you unlock him in the Story and at the Tower once you complete the game.
When trying to grind out Reputation for Vanguard Tactician Engrams it is wise to obtain and use a Ghost that will reward you with additional Vanguard Tactician Tokens upon completion of Strikes.
Commander Zavala accepts Vanguard Tactician 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 Commander Zavala:
- Faction Helmet (Class Specific)
- Faction Gauntlets (Class Specific)
- Faction Chest Armor (Class Specific)
- Faction Leg Armor (Class Specific)
- Faction Class Item (Class Specific)
- Vanguard Magnus Shader
- Faction Grenade Launcher: Wicked Sister
- Faction Hand Cannon: Daedalus Code
- Faction Pulse Rifle: Nightshade
- Faction Shotgun: Deadpan Delivery
- Faction Sidearm: The Last Dance
- Faction Sniper: Persuader
- Faction Submachine Gun: The Showrunner
- 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 Commander Zavala.