Garantie in German means "Warranty" or "Guarantee". I think that is "Guaranteed from Solingen"(or "Guaranteed of Solingen quality"). An expert could say more on this.

The funny thing is, I have a Swedish J.A. Hellberg razor with almost the same mark etched into the blade with "Skydds Märke"("Registered Trademark" in swedish) etched beneath it. Maybe it a logo used by various cutlers to signify a common thing. But again, you need an expert on razor companies.