The Orc who knew too much

[Boromir88]

Ugluk's warning to Grishnakh has always interested me:

"You seem to know a lot," said Ugluk. "More than is good for you, I guess."~The Uruk-hai

This is Ugluk's response to Grishnakh talking about the Nazgul, and how Sauron will not unleash the winged Nazgul just yet, "they're for the war, and other purposes" he says. Then later, it becomes evident to Pippin that Grishnakh knows about the Ring and he is able to trick Grishnakh into thinking he has it. It's one of my disappointments in the movie, because Grishnakh is shown to be driven by just wanting to munch on some hobbit legs. We miss out on an interesting orc, as well as Pippin's development, to be quick thinking and resourceful! Anyway...

For an orc, Ugluk's right, Grishnakh seems to know a lot. How did this happen? How did this come to be, because orcs I've assumed just can't be trusted for such an important tasks. Or trusted with "classified" information, such as knowing about the One Ring. Look at what happens between Shagrat and Gorbag, they only seem to vaguely know the boss wants a "weapon" for the war. Grishnakh, however, appears to know specific details about the Ring, the Nazgul, and Gollum's capture.

It's different than Shagrat and Gorbag's vague understanding and Ugluk's guess comes true. Grishnakh's demise is because he knew more than what was good for him. How did he become such a learned orc?