The Hosidius favour certificate is a quest reward for completing The Depths of Despair.
Reading this grants the player 10% Hosidius House favour. There will be a confirmation message before doing so. It is suggested to abstain from using this if players are already progressing towards locking in favour in another House, as using this will cause favour in another House to decrease.
Should the player wish to use it some other time, they can destroy it (if bank space is an issue) and reclaim it from Lord Kandur Hosidius.