I assume you're trying to make a distinction between urgency and importance here - I think priority should reflect both, but that's a personal view.
The sort options within the priority view are fairly limited: Map Order, Alphabetical, By Start Date or By Due Date. About the only alternative here is to assign a prefix, like "A." to the names of the really important topics and sort alphabetically.
As an alternative to sorting you could highlight the important topics to make them stand out in the Priority 1 column by assigning a different fill colour to them, or adding a coloured tag, another icon, etc. To emphasise this more you could filter on whatever attribute you choose using the Fade feature which would leave the other topics in the same column in place but faded.