Asher Mir is the vendor in Destiny 2 that deals with IO rep. He is located on IO near The Rupture landing zone. You gain access to Asher Mir after playing through the main missions on IO.
When trying to grind out Reputation for IO Engrams it is wise to obtain and use a Ghost that will reward you with additional IO Tokens upon discovering other IO Tokens.
Asher Mir accepts IO Tokens, Phaseglass Needles and Phaseglass Spire in exchange for reputation points. 20 Tokens will be required for a full level of Reputation. It will take about 100 Phaseglass Needles or 20 Phaseglass Spire for 1 full level of Reputation. Once you have handed in 20 tokens, 100 Phaseglass Needles, 20 Phaseglass Spires or any combination of the three 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 Asher Mir:
- Faction Helmet (Class Specific)
- Faction Gauntlets (Class Specific)
- Faction Chest Armor (Class Specific)
- Faction Leg Armor (Class Specific)
- Faction Class Item (Class Specific)
- Echoes of IO Shader
- Flowers of IO Shader
- Faction Fusion Rifle: Tarantula
- Faction Grenade Launcher: Berenger’s Memory
- Faction Rocket Launcher: Blue Shift
- Faction Shotgun: Baligant
- Faction Sidearm: The Rattler
- Faction Sniper Rifle: Widow’s Bite
- Faction Sword: Unspoken Promise
- 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 Asher Mir.