I believe I read (official source?) that beam weapons have 100% accuracy. So if you research "Targeting Specialization" which gives you +10% accuracy on all weapons, does that mean that it gives no bonus to beam weapons (which already never miss)?
I'm suspecting that beam weapons are not 100% accurate. According to the Wiki the Thalan tech tree gives "Beam Shifting" allowing a specialization of "Ship Beam Accuracy 0.1" which I assume increases the accuracy of beam weapons by 10%.