Blame the localization team.

The JP version calls them:
The Binding Coils of Bahamut 1
The Binding Coils of Bahamut 2
The Binding Coils of Bahamut 3
The Binding Coils of Bahamut 4
The Second Coils of Bahamut 1
The Second Coils of Bahamut 2
The Second Coils of Bahamut 3
The Second Coils of Bahamut 4
The Second Coils of Bahamut 5
The Final Coil of Bahamut 1
The Final Coil of Bahamut 2
The Final Coil of Bahamut 3
The Final Coil of Bahamut 4
Alexander: Gordias 1
Alexander: Gordias 2
Alexander: Gordias 3
Alexander: Gordias 4