This passage reveals that the warrior culture of Beowulf's time valued? mental clarity
physical clarity
showing mercy

physical clarity since beowulf was valued for being as strong as 50 men

Explanation:

moon-letters were a method of writing invented by the dwarves. moon-letters were ordinary runes, but written in such a way that they could only be read when the light of the moon shone behind the writing. some moon-letters could be read by any moonlight, but it was possible to make the writing even more secret. more sophisticated moon-letters could only be read by the light of the same shape of moon, or at the same time of year, as when they were written. hope this !

the answer is irony!