Condition to compare 2 binding values

I’m trying to create a condition for a Data Trigger that compares the value of whatever is referenced by the binding on that trigger to the value returned by another binding. All I can see is an ability to compare the binding value to a hardcoded value supplied in the Value field.

Is there some mechanism to allow two binding values to be compared so an action can be taken depending upon whether or not they match or if one is greater than/less than the other?

No. That is not possible. The Value field of a DataTrigger is a constant.