I suggest the Aegis of the Immortal or Aegis of Immortality get an animation similar to the Radiance inventory Icon.
This is a one of a kind rare item.
Perhaps the core of the item could pulsate in glows like a heart beating and as soon as the Host-hero dies the claw fingers open up,the glow becomes brighter and a drone-sound builds up in a frequency and the icon disappears from the inventory and the sound stops.
All this happening in correlation with the physical resurrection animation of the hero on the battlefield.

http://www.dota2wiki.com/wiki/File:A...e_Immortal.png

There could also be some sort of visual indication for allies which hero is carrying the Aegis,but that is debatable.