The helmet of the esteemed infantry general Seleucus of Seleucus of Nicator, this man served under Alexander "The Great" during Alexander's conquests. Following the partition of Alexander's Empire, Seleucus started his own "Seleucid Empire" and went on to re-take all the territories of the East that were taken by Alexander, making Seleucus the one who had taken most of Alexander's former territory (and completely took the East back).
Now, in Morrowind, one may be able to recover his helmet. How it is there is beyond me but one thing is for sure - it is a relic of an old time, and a powerful relic at that. Use it well.