I don't seem to recall this sentence from the associated lesson. It might have appeared in the new kanji vocab after the lesson, but I do not know how to check if it did.
#Sentence in the card does not appear in lesson P1 U39
gentle spear
hoary onyx
This sentence doesn't appear at all in that lesson, but it is associated as a lesson flashcard for some reason. I don't think it fits here though and would probably be more appropriately associated with the Vなさい lesson (P1 U121), but I'm not sure how difficult it would be to change that nor how it would affect current learner progress. Maybe @gray harness would know