I use AJAX to defend my gate. With the new equipment slots I used slot I for attack mode and used slot II for defence mode for when he defends the gate.
I then went to my hero statue and chose slot II for AJAX. The statistics were showing as if he was equipped with slot I items - I wasn’t sure if this was a display error or a bug. I left it as it was and when I next returned I’d lost HEAPS of trophies so I assumed AJAX was actually using his attack items in slot I rather than his defence items in slot II. I did a check my running a mock attack on my gate and he was actually using slot I items.
It seems that if you choose slot II (and I assume slot III) for your hero statue, it will ignore that and use slot I.