Demro was much indebted to Sentinel Memnes in the Eltnen Fortress, and wanted to help him with his work. When you went to meet Memnes, he told you to go to see weapon researcher Coeus in Sanctum because it was Coeus, not Memnes, who needed help. But what Coeus wanted was Kerubian weapons. Coeus asked you to procure some of them. You returned to Memnes and conveyed Coeus' message.