Там как раз от юнита и смотрится. В примере даже есть.
Allocating Wounds
In this example, two Space Marines are firing at a unit of Orks. Space Marine X has a missile launcher whilst Space Marine Y has a boltgun. The Space Marine player can choose which weapon to shoot first. The firing player selects to shoot all missile launchers in his unit first (in this case it is just Space Marine X). He chooses to fire a krak missile, and hits and wounds. This Wound must be allocated to Ork A, even though Ork B is closer to the Space Marine X, because Ork A is closest to the Space Marine unit. After completely resolving the missile launcher attack, the Space Marine player then selects boltguns, and fires with Space Marine Y