Longsword:
weapon length: 106
weight: 1.8
difficulty: 10
speed rating: 99
weapon length: 106
thrust damage: 23 pierce
swing damage: 37 cut
slots: 2
Secondary Mode
Arab Cav Sword:
weapon length: 105
weight: 1
difficulty: 13
speed rating: 95
weapon length: 105
thrust damage: 19 pierce
swing damage: 33 cut
slots: 1
Somehow all your claims are somewhat incorrect, it's one shorter, 4 slower, and it got 4 swing damage less.
Our little cheeky noob should go read this
http://forum.meleegaming.com/beginner's-help-and-guides/game-mechanic-megathread!/1h R to L+19
2h R to L+13
That makes 1h longer in that case and many more.
R to L is definently most used swordcav swing... oh and about the speed, 2h gets way more speedpenalty on horse than 1h (does it even get any?) So there are you're hard facts, now go spam your 1h proud of this information :p
Back to business, it's not really even the 1h sword that makes the class op compared to 2h, but the shield. Say a 1hcav is reared and you try to swing him from behind. No can do, if he can turn his horse like 10 degrees to you, turn his char and raise shield you can't hit him with a swing.
Also just the pure risks of using 2hcav must be rewarded some way!