Metarln
It's ridiculous how you think Excaliber would only be able to threaten Ottar, how stupid. Have you read Type Moon seriously? Even the sealed excaliber's normal slash can kill Ottar easily without the need to unleash its power. Also, Exaliber without seals is an ex-rank Anti-world Nobel phantasm, stronger than enuma elish because of its nature as a weapon that defends against foreigner threats( enemies from different worlds, or outside the the known universe)