This is "Blaster Blade", the First Knight of the King of Knights, "Alfred", in his younger days. At that time, he was a mere member of the royal guards in terms of title, but his bountiful talents had already bloomed, and his achievements made him the most impressive swordsman of the knightly order.
In addition to his inborn talents, he never neglects self-training. It is reasonable that he is the only person who can master the original "Blaster Armament" developed by "Blasteed", given that he is recognized as a man of diligence by all.
After "Second Invasion of Ubiquitous Ogre", he gained the honour and actual power to serve as the First Knight of the King of Knights, but he officially handed the title of First Knight to "Galehaut". For this, he served the king as the Second Knight ostensibly, but from the view of history, it is obvious that he is whom the King of Knights trusted wholeheartedly.
His bravery has been recorded in all sorts of documents, but he has disappeared since a certain era. Whether he has taken a journey of wander, has been active incognito in other nations, or is reborn as a dragon underneath the Sanctuary--- many hypotheses have been raised, but none knows the exact truth.