I don't just want to make a post that simply complains about the new custom ability icons, you can find enough of that on Reddit.
However, I do not think custom item icons should be displayed to opponents, and here's why.

The first, is that unlike ability icons, items are generally associated to their images alone.
What I mean by this, is with a custom ability icon, I always know that a particular hero will always have those 4 skills, in those 4 locations (AD doesn't count ).
Items, however, can be moved around as much as you like. On top of that, a particular hero does not necessarily require particular items.

The reason custom item icons introduces a fundamental gameplay problem, is that unlike hero skills, it is commonplace to need to quickly check a hero's items.
This means we need to be able to quickly identify what they have, based on any ordering they choose.
The reason this isn't a problem with skills, is we are unable to check what they have skilled regardless.
They are perpetually greyed out to the opponents.

Anyway, please reconsider.

Also, that custom blade mail icon looks nothing like a blade mail. If anything, I would have guessed it's a crimson guard.