A Roman/Byzantine Spathion of the Galovo type.
The 10th century byzantine spathion was an evolution from the late roman spatha, which was a cavalry sword. Following influences from Goths and Vandals, the spatha was passed on to the infantry, replacing the traditional shorter gladius. In the following centuries, and as Maurice’s Strategikon suggests, influence was also born upon by Sassanids, Avars and other steppe nomadic cultures. Nevertheless, evidence suggests that the infantry byzantine spathion didn’t become that much longer than it's ancient roman predecessor.