Why was Borus amused?
It was not just because he could very well take these two as his physical strength enhanced with his semi-Devil physique had long surpassed their capabilities, the real reason was that he genuinely found the situation funny.
He was merely to bide time so that every body on the battlefield of Gelread valley could be carted away by the beasts hurrying about behind him.
As for the Lieutenants, while they did summon their Armaments and charged Auroras, they did not attack immediately as they were still outnumbered.
Let it be mentioned now that it was not just the two vocal lieutenants that were present. There were others, they just declined to comment and followed the lead of the vocal duo.
Anyway,
Well aware that these beasts far outnumbered them and their capabilities were still relatively unknown, they were only waiting for reinforcements and that was when a phenomenon occurred on the side of the valley.