Board Thread:General Discussion/@comment-86.169.78.147-20150412145140/@comment-13268839-20151031193738

Well, Kayaba isn't necessarily evil, he was acting on his childhood dreams... but he did things that were unexcusable, yeah. I don't consider him evil in the sense that his goal wasn't to kill others — it was to make a reality out of the floating castle that had once appeared in his dreams.

As for the sword itself, apparently the two, the Elucidator and the Dark Repulser were somewhat outdated by the 75th floor. Lizbeth had commented at some point that though they were almost maxed out, enhancement-wise, a similar boss-drop (though they're not easy to get) from a more current floor would probably top it with a quarter of its enhancements, or something around that. If they had realized after the 80th floor boss for example, or the 85th, Kirito may have needed to replace those iconic dual blades. Durability-wise, they're probably below that of Kayaba's gear.

... that being said, in Alicization, Kirito uses a pitch blade sword, whereas his new best buddy (who, by Kirito's own words, might have surpassed him) uses a light blue one. Coincidence? Possibly, or Reki just likes those colours.