The Flechette is a small exposive device that can be stored in the inventory; when used its effect vary depending on the charater using it:
Baratus: Can be thrown like a grenade.
Parias: Can be dropped and will explode shortly afterwards, spreading poison gass; the cloud lingers for a limited amount of time. Remember to move out of the way quickly.
Daedolon: Can be dropped and will explode after one second causing direct damage to a target. Remember to move out of the way quickly.