In regards to your question, what invokes the selected features on the map? This will help me understand how to approach your particular workflow.
Any method that can be used to select a feature. Click on it in the map, select it from the list, etc. The default method of distinguishing what is selected is by means of a highlight. I have found that this does not provide enough in terms of distinguishing the selection.
This type of functionality is very custom since other widgets can do the selection as you mentioned above. You could do a hitTest on the click event for the map and then use a graphicslayer to hold the results then add your custom symbol. However, any selections from other widgets like list or table will do the normal selection. Perhaps this is a requirement we can add to the map widget that allows you to add a custom marker symbol for the highlight option.
I am curious though regarding the highlight selection, can you provide an example of how it doesn't distinguish enough? We could share this with the JSAPI team.