What are these fast zombies of which you speak? 
Re Armor
I haven’t worn plate in a long time, and even that was only to see how it felt. While I agree the weight is often exaggerated, I think maneuvarability would still be reduced. This was illustrated when the owner of the plate I had borrowed told me to lie on my back and try to sit up. Unless you are an olympic specimen, plate means having to flip onto your stomach to stand up. This only takes a second. But it involves turning your back on oncoming zombies and using both hands to push yourself to your knees.
I wonder what Trek style phasers would do?
On highest setting, it vaporises things, but what would a wide area sweep on stun do to a zombie?
A light saber might be useful…
I’m guessing, nothing. We’ve seen repeatedly that strong enough organisms can withstand the stun setting. Uta of the clan Trelesta is hit with everything from lightest stun setting to just under disintegrate. Her genetically engineered body, is slowed for perhaps two seconds by the highest stun setting. When Geordi is captured by Pakleds (they look for things and make ships go), they repeatedly shoot him with a light stun setting. Dr Crusher worries about the cumulative effect. But, Geordi doesn’t seem to be more effected than he would by a conventional light beating. Given the changes in how a zombie’s nervous system functions, I can’t see the stun setting doing any good.
However, Star Trek technology does allow a modification of what is surely one of the wisest tactics ever ‘Take off and use the phasers to incinerate the biosphere from orbit. It’s the only way to be sure.’
But, if we’re discussing completely fictional ways to deal with zombie plagues, technology is not the way to go. Forget phasers, rail guns, forcefields, etc. I want a bunch of clerics turning the undead and a bunch of mages throwing spells. Of course, mages and especially clerics give human beings a connection to great powers and proof that there are deities who care about us. Such things are antithetical to the spirit of most zombie films. In Romero’s films, we are animals scrabbling for survival in a meaningless universe and if God exists, He is silent and indifferent to our suffering.
A couple of problems with that. First, nobody in the Trekverse can hit a human with a fatal shot, unless that human happens to be wearing a redshirt. Second, the phaser beams move so slow, that even zombis could dodge them.