If Spathion sucks, Knightly Arming Sword must be awful, because at +3 it has 3 less thrust damage and only gives up one speed.
Something about the 100+ length 1h swords makes them seem way slower than their rating; military cleaver seems faster than the KAS/NCS/spathion/paramerion, despite having a slower rating. My +3 Arabian Guard Sword is rated at 99 speed, but it feels clunky in duels. Meanwhile, a Grosse Messer or Side Sword (same 99 speed) seems nimble. It's probably all in my head.
I was using Draeth's +3 Liuyedao last night, and to my horror, I performed way better than I usually do. I prefer the look/playstyle of the more "substantial" swords, but something about the 85-95 length/100+ speed 1h swords just makes them more effective.