User blog comment:Jopjopjop/Volume 18 Spoilers/@comment-82.242.251.205-20140623232716/@comment-82.242.251.205-20140626133915

Hauteclaire is the sword of Olivier, a character in the French epic "La Chanson de Roland". Since it's a French sword, the name must be in French.

Example: The other French sword Durandal is writing "Durandal" and not "Durendal".