Good point, but I think it is worth noting that this is less a matter of the weapon being powerful/effective than it being flexible in terms of how we power it.
Normally we would want to power Offensive abilities with player dice (preferably from trees specializing in Offense). Using Focus actions for such a thing would be horrendously inefficient; something like getting 3 Offense successes in place of 17 Growth successes. But this power let's us use the focus dice at full efficiency.
To be clear, this normally not a significant boon. Most of the time, if we wanted to attack something, Root trees could just do that with their player dice while the Focus action remains targeted at growth. This is equal in efficiency to an appropriate number of root trees working on growth while we use the focus action on Offense. The actual gains come in case we want to output more burst power than can be accomplished by swapping dice around. With a different weapon, as soon as we ran out of offense-specialized players, our efficiency would fall - and once we ran out of player dice at all the focus actions would do little. In contrast, this Offensive action will accept Focus actions at their full undiluted efficiency.
In summary, for small attacks lasers are nothing special, but if we want MOAR POWER lasers will be able to "accept" far more energy than other weapons. And I can see that being a big deal.
