It is a quest reward for completing the quest Unfathomable Depths.
- With the 25% bonus, Dwarven armor's rating is slightly diminished compared to that of ebony armor, making it a fairly strong armor set.
- Ancient Knowledge gives 25% armor bonus to all armor types except Dwarven armor. This can happen even after the official patch 22.214.171.124.8 that supposedly has the fix for the bug.
- Even though the effect's description says it only improves how fast Smithing can level up, it may improve how far armor and weapons can be upgraded instead.