Here is a VERY ROUGH draft I just put together.
Its obviously open to significant improvement, but the concept is there.
On the left you have your CRAFT and REPAIR buttons.
This left 'pane' will completely change depending on whether you are in the CRAFT or REPAIR screen.
REPAIR will show only repair slots, with items most damaged appearing at the top of the Inventory screen.
CRAFT will show only the "Weapons/Armor/Banners/Artifacts" display. With buttons for LI/Archers/HI/Cav/Heroes that appear below when you click on them. Fragments will appear at the top of the Inventory screen.
The Inventory area can show MANY MORE items. You could have a scroll bar, or even a 'page' select.
Perhaps there could also be a third screen called "VIEW" or "MAIN", where you get a FULL inventory screen, and there could be filter options for the various types to use.
Right now we have so much wasted space.
Functionality > Pretty.