I am not sure whether this really works but it might be worth a try
Create a missile weapon with invisible projectile and give it a nice exhaust simulating the laser effect. Make the missile extremely fast which results in almost instant impact and a nice laser trail. Then you give that missile weapon a minimum damage of 0.1 but a DetonationOCL which creates a dummy object that kills itself in say 1000 msec, firing the real weapon. Don't forget to give the laser effect particlesystem a really long lifetime so that it's still present even when the missile is already gone.