Please consider adding different bonuses to at least already existing items.
There are heroes that can have a lot of items that buff their abilities.
For example, look at Avalon, or Elena, or Bane - they can have 3-4 slots fully adapted for their skills.

Other heroes, on the other hand, have little or none buff at all.
Please just add these bonuses to already existing items (we can look at divine items):
Heartpiercer, Blink dagger, Sultan's Fist, Blessed Elvenblade, Galastic scepter and so on.They all only have stats, but no hero buffs.
Why?
Can be added bonuses for Nora, Mako, Yip, Denji, Wraxius.
Maybe some other abilities of other heroes, but it will at least make these items useful.

I doubt that many people use Sultan's Fists or Heartpiercers on their heroes.

While I agree, that would require rebalancing (at least if those buff monks/rockets even further).
Would like it for other skills for sure. Mako got +1EagleEye at least.

Agreed. Huge percent of the items are useless...

I will put it on the list.