High King of the Known Worlds
A tarnished cavalry sabre, the Oughtsblade seems old fashioned and out of its time. Its weilder can summon a spectral silver horse. (Love the fourtiesblade.)(I think all the blades for the second half of the century have already been mentioned, and I couldn't think of a good theme for the first blade of the 1900s.)
With all the different ideas, I’m thinking the blades change based on the weilder’s knowledge of the decade in question. Setting wise, let’s say I don’t know, because... quantum... but from a mechanics standpoint, this lets players tailor their characters instead of being locked into a role based on the blade, and let’s other players take up fallen swords without having to play the same character as whoever had it before.