A verdict is a judgment/decision made by the judge. A noun that is denoting something immaterial and abstract is an abstract noun and a judgment is abstract, therefore, verdict is an abstract noun.
An abstract noun is a word for something that can't be experienced by any of the five physical senses; something that can't be seen, heard, smelled, tasted, or touched.
The noun 'verdict' can't be seen, heard, smelled, tasted, or touched. A verdict is something that is understood, a word for a concept.
Yes, you can hear someone read the verdict or see it written on paper (screen), but the voice and the words are not the verdict itself. The written or spoken form is simply a communication of a verdict (a decision).