Lord Lucien
Lets all love Lain
Achilles' sole defense here is his shield. At the rate Legolas can fire those arrows, and with that accuracy, Achilles will know that he can't break from cover to throw the spear. Legolas is also accurate enough to target Achilles' legs. Given the size of his shield, Killees' extremities are very exposed. In his match against Boagrius, the shield covers just above the tip of his helmet down to his pectorals. That's a lot of abdomen, pelvis, and legs for Legolas to target.
Assuming even that Achilles' shield can withstand all those arrows, it will be a very, very slow advance toward Legolas--and that's assuming that Achilles' can block every shot. Which I doubt.
I'd give this to Legolas, at least 8/10 times. Maybe Achy can huck his spear and take Legolas with him a few times.