Part of me wants to address everything, but I think this decision has been delayed long enough by me wanting to be excessively thorough.
Briefly, I will explain that, the way that Athos' attack has been seen by myself and Dato is not that they are coming as the picture depicts in a wide up and down fashion akin to mortar fire, but more like the truth seeking balls in that they start out with a linear path, not a parabolic descent.
Even with that viewpoint, I am still skeptical of your speed buff's magnitude. Athos fires off the balls, some of them head towards you. You move 1000 yards in an unspecified arc in what is certainly less than 3 seconds. Assuming that the arc is not particularly sloped (almost linear really so as to make the following estimates more reasonable) and that is indeed 3 seconds and not sooner, then you are moving about 333.333 yards per second, or about 681 mph, just under the speed of sound. If you move 1000 yards in 2 seconds then you have long breached the sound barrier and caused a sonic boom (500 yards a second).
Lightening your load is one thing, but need I remind you that your character is not exactly aerodynamic:
1) You have a sword still withdrawn. However shorter than a katana it is, you never stated putting the special shortsword (the Weaknessless Soaring Shortsword) back in its place.
2) On each hip from the beginning of the fight you have two more katana.
3) 5 watertight scrolls that have whatever sealed in them.
4) Two more additional item pouches.
5) Greaves.
In descending order of what would surely affect your movement if it stayed attached to you, I find it highly unlikely that all of this stays on you while moving at these kinds of speeds, nevermind being able to even get to those kinds of speeds with so much adding to the forces against you moving fluidly through the air nor not one of the fist sized balls clipping them.
Even Sasuke dodging Danzo wind bullets got grazed by one of them.
My ruling is that I see no way for you and everything on you to be completely unaffected by Athos' spheres, nor that you quite get to 1000 yards this post (let's call it 500 yards instead). If I tell you that you have to lose one of your items to falling off or even grazing, then that would give Athos your location and he could, presuming that the homing balls can also go upwards, send them after you long before you get to the 1000 yard mark, which could result in more grievous injuries.
I am torn between declaring you dead this post or just forcing you to accept some damage to your person and have Athos follow up in his next post. Granted, depending on how it is done, the latter does give you a chance to try to survive as you will have more options given to you, but that would require arbitrarily deciding what on you gets vaporized and what stays.
I am not sure if I could even ask you two to come to a consensus on that sort of thing given this thread, so I am settling on:
The arm with the shortsword, gone almost right to the shoulder blade (causing you to drop the shortsword), the ordinary katanas both sheared almost to the hilt, and your hairbun and the capsules with the scrolls vaporized as well.
If you feel that that is no better than dying, then you are free to take that option as well.
That's my ruling, and I do not envy Trev's favored judge position one bit at this point.
[P.S, still ended up with a super long post.]