Click the add-on button to launch a tab which will take you to the bungie website. If you are not logged in you will need to be. Once you are logged in it will automatically recreate the page for your easy item management pleasure.
Drag and drop items from one character to another.
Double-click to equip items.
Drag profile to the target character to apply the profile!
See the number value stats for weapons.
Advanced feature -> Bookmark other players profiles to quickly glance at what they have equipped.