From Destinypedia, the Destiny wiki
Crucible Commendations are items added to Destiny in The Dark Below that are awarded with Crucible rank-up packages beginning at rank 3. They are required to purchase Legendary weapons, helmets, and chest pieces from Arcite 99-40, Lord Shaxx, Executor Hideo, Lakshmi-2, and Arach Jalaal, in addition to a sum of Crucible Marks.
Upon the release of House of Wolves, Crucible and Vanguard Commendations will no longer be necessary to acquire vendor gear and will cease to be awarded in faction rank-up packages. The player will be able to use any leftover Commendations to provide an additional 250 points of reputation towards factions per Commendation.
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