How do you change the Arbiter's cloaking field or give one to other units?
In Arsenal III, select your unit, go to the AI/Orders tab and change its Computer AI Idle and Human AI Idle to "Initialising Arbiter"
The cloaking field of a unit is determined by the range of its ground weapon, so you might want to give it one of those as well.
Sweet, it worked, thanks.
You're welcome

If you want to do an experiment, try giving the scanner sweep (yes, the spell unit) an Arbiter cloaking field. If you can explain what happens and why, then you can have a cookie, and you will probably learn something about making units disappear...
It cloaks your units that you sweeped.
Two screenies showing how the zealot does nothing to my SCV's that are attacking him.
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My guess is that the scanner sweep detects that there's still a cloaked unit there, but since it recloaks it self then it just keeps cloaking and un cloaking so you can't target it. There were a bunch of cloak/uncloak noises going on where there were units that I used it on.