Mmh so the a hero armed with the sword civilized the people and formed a nation (as seen in them starting agriculture) but then there was a rebellion/civil war and the sword went missing.
Seems like the civilization of the Tellurion arc have lived peacefully until generations passed and laziness took over. People forgot their amazing advanced past for petty tribal squabbles, ruining the once great civilization. The sword is a physical representation of that past giving regained hope for the future generation like the Shield Boy here.
Well, whatever it means, it clearly means he's found some kind of hope, even in his present circumstances. Wow, this really got me right in the feels. Amazing job! Keep up the great work!