The sword hidden in Sicarl Mountain, which belonged to the previous owner of the "Demon Hunting Seal" held by Shard, was actually owned by the ancestor of the eye doctor from the distant past.
As for why the High Ring Sorcerer didn't place these two relics together, it wasn't clearly written on the parchment Shard received from Mr. Alfred, the eye doctor. The parchment only mentioned the location of the sword and the concealment and defense measures taken to prevent it from being taken by others.
Although that had happened eight hundred years ago, since it was arranged by a High Ring Sorcerer, Shard believed the likelihood of the sword being taken was very low. However, as times change, even Sicarl Mountain itself had undergone many changes over those eight hundred years.
Thus, even with the position confirmed by the evening sunlight and a detailed map of Sicarl Mountain, Shard could not guarantee he would definitely find it.