Flame Number was also carrying a big bird—Landwalker bird Loki.
In the battle at sea, Liszt did not intend to ride the Dragon to show off his might; doing so would be too ostentatious, like using a cleaver to kill a chicken.
So he simply brought Loki along, ready to ride it around to capture Sky Knights.
Loki was just an Intermediate Dragon Beast, with average flying speed, but it excelled in its powerful jumping ability, which allowed it to leap from one ship to another. This was especially useful in boarding battles, for capturing those Sky Knights trying to escape, with the only caution being to not get shot to death by arrows.
After all, Loki was just a slightly stronger Dragon Beast; its defensive strength was not great.