I was unable to find the syntax to do this, so if I'm just blind let me know... but, please consider adding an "item variable" for items conditions that works like the custom texture field in a Conditional Icon. This will enable players to target an item slot to be evaluated instead of a specific item for that slot.

Example:

Conditional Icon
Condition: "Item has on use effect" and in the "Item to Check" box we are able to put $item.10 to evaluate hands, or $item.13 to evaluate trinket slot # 13 for an on-use effect. If the effect exists and is not on CD, then the condition returns True. If the item has an on-use effect and is on CD, then the condition returns false.

Thanks.

This is a thing, though instead of $item.13 you'd enter "13".
As for syntax it can be found in the tooltip of a what to track box of an item cooldown icon, but is indeed not present in the condition(s) tooltips.

Its also in the suggestion list and the tooltips for the suggestion list

Alwies gave the correct answer by entering the slot number... @ascott18 the suggestion list lets you pick an item to watch, not a slot... and the number next to the item is ambiguous. When you pick the item, it enters the item, not the slot... but A for effort.

@Allnuerizym The first 10 items in the screenshot in the suggestion list are showing the item slots, my friend. See the item slot numbers along the right-hand side? The tooltip also clearly explains what will happen when you choose that item.