Derfflinger



Derflinger is an old sword that Louise was able to buy for Saito. Louise spend most of her money in order to pay for an expensive healing potion for Saito after a fight early in the series, forcing her to buy Derflinger due to its cheap price of 100. Derflinger has the ability to speak and is seen to be very intelligent, often offering useful information at times.

"Derf", as called by Saito, provides information on whatever subject he may remember. Despite being a legendary sword, in the light novels Derflinger often forgets some information due to being an old sword. In the first season, he is always called 'annoying' by Saito and Louise. However, as the series progresses, he is proven to be very useful, being able to recognize Louise as a Void Wizard, Tiffania as an Elf (but possibly, he may also know that she is a Void) and was also able to deduce Sylphid as a Rhyme Dragon (Irukuku) in disguise, as well as Bidashal the Elf and the Jormungandr's Counter ability (that can only be penetrated by Void magic and/or Earth technology).

Notably, Derflinger is known in the second season as someone who either Louise or Saito come to for romantic advice (He was the reason for Louise to ask Saito to marry her) despite being only a magical item that possibly cannot experience feelings of love. But this is proven to be false since he feels happy when with Saito, sad when he learned of his death (until Tiffania cured him) or just teases Louise about her feelings for Saito whenever possible.