Acceptance that someone else is right then you, jeez. Obviously you can slash as many times in a jump as the delay allows you to, You can do it with a speedy dagger as well. What is not possible is like a 5 bf's in 1 jump because the block delay is to slow for that.
Also dagger instafall is possible, you have to lunge someone while he is in the recoil animation. It's been proven & acknowledged by your favorite dagger heroes.
