The two phoenixes, as large as elephants, were all bound to the ground, giving Liszt the opportunity to closely examine the phoenixes, which are known as Sub-dragons.
Sub-dragons are considered Super Dragonkin Magical Beasts.
Theoretically, they are second only to dragons in strength, but Liszt felt they did indeed possess some power, yet to claim they were second only to dragons seemed to somewhat underestimate the gap between magical beasts and dragons. The disparity was vast, akin to the chasm between ordinary knights and Dragon Knights, or perhaps a rift.
No wonder even Noble Landlords who aren't Dragon Knights also think of venturing into the mountains to capture phoenixes; it seems these Nobles have an understanding of Sub-dragon magical beasts.
They know that the power of a Sub-dragon is limited, belonging to a capture-able category.