Even although Frenzy is a special ability and Laser is a weapon ability, their wording is a case of clear copy paste. However in Laser, the book explains in detail how it should combine with Sustained Attack. Such explanation is absent from the description of Frenzy.

Would you rule it as the same ? (I mean, you roll Combat dices, re-roll for sustained attack, and then for each success you roll one extra dice which has no re-roll for sustained attack, as per laser description)

You are right, there is no clear ruling and no good way to deduce it from ther REROLL rule.

I suggest we put it on the list of rules to be clarified for the next errata.

Yes, I would rule it the same. I believe the reason it's clearly put forth on the laser rule is because of the issue with the laser rule in DT. In DT the rule explained it how it works, but the example was exact opposite, and it caused quite an uproar until properly clarified. They should, as tapiercheisse alludes, have made Frenzy explicit as well.

It works the same as lasers for one simple reason: the rule says you roll for additional attacks after the attack roll is made. Your not done with your attack roll until you make your re-rolls, because you are still rolling.

Very good point. There's our answer.

Nice.

Thanks folks