This was tested with the Y2 exotic rocket launcher Truth, but theoretically any Y2 exotic heavy weapon should work the same way.
- Purchase heavy weapon telemetry, if necessary, from the Weaponsmith for 250 glimmer and 5 weapon parts (which can also be purchased for 250 glimmer from the Weaponsmith)
- Activate the telemetry
- Purchase heavy weapon from exotic weapon kiosk for 1 exotic shard and 2500 glimmer
- Equip the new exotic heavy weapon
- Burn 6 Motes of Light
- Unequip the now fully-leveled exotic heavy weapon and dismantle it
- Repeat steps 2 through 6 until out of glimmer or Motes of Light
Each time you dismantle the fully-leveled heavy weapon, it will return two exotic shards, a few hundred glimmer and 2-4 Motes of Light. This effectively gives you an exotic shard for the investment of 2-4 Motes of Light and about 2200 glimmer each.