I actually think its implied to be tied to the 4+ roll myself but can see how you can read it as not being.
Each time another aeldari model is slain within 7" of the visarch, roll a d6.
On a 4+, the visarch immediately regains a lost wound.
If the slain model was a character, add 1 to the visarchs attacks characteristic for the rest of the battle (to a max attacks characteristic of 7).
I can see how this can be read as independent of the D6 but if you take out the middle sentence to make the 3rd stand alone, why do I roll the D6? they seem intrinsically linked on the roll for reward
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