Currently, applying a cursor to an element requires the designer to either know, or look up a reference of the available WPF cursor types, and manually type them in.
As (with the exception of the Custom cursor option) there is a set amount of Cursor options that can be applied, it makes sense for us to include the cursor types in a dropdown rather than as a text input field.

Attached, you will find two suggestions. A cheap 'text-only' version, and a slightly more involved 'plus' version which exceeds what Blend and VS offer, which would give the designer a visual preview of the different cursor types if they aren't familiar with what each looks like.