I don't know if this helps anyone, but I tend to think one application of the Blend skill as being applicable when the enemies are not active. Whereas Sneak, is when the enemies has been alerted already, or are deliberately watching out for something.
Being disguised as an enemy soldier and trying to avoid drawing attention to oneself while traveling with the army is Blend
When the army stops for the night, and you try to leave while everyone is asleep you use Sneak
When the sentry spots you and asks: "Where are you going?" you respond with a Bluff
Blend is sneaking in plain sight.
To use another Star Wars Example, in A New Hope, when Han and Luke are disguised as stormtroopers and walking around the Death Star, specifically when they shake deny the officer from getting in the turbolift with Chewbacca they are using Blend
. When they are asked "Where are you taking this thing
?" and after the shootout when Han is talking about reactor leaks on the intercom these are example of a failed Bluff
check. When they get out of the Storm Trooper outfits, and are going around the Death Star in their plain clothes (where did they keep their boots?) and avoiding patrols that is Sneak
Example number 3: When a hunter is just walking through the woods, searching for a rabbit, and dressed in camouflage, but trying to not to alert anything that would be a Blend
When the hunter finally gets close and the rabbit sort of perks up it's ears, the hunter has to start making Sneak
When the rabbit starts trying to tell you it's actually duck season, that's a Bluff
Carousing a fancy ball for information when you don't have an invitation and not getting kicked out is a Blend
Convincing the Duke of Farnigal that you are the 7th heir of the Royal line is a Bluff check.
Having a quiet rendezvous with the Dukes daughter in the room next to the party is a Sneak
check. I'm sure you could argue that other skills could be used, but this is a pg board.
When you're caught in flagrante delicto
and have to jump out the window that would be an Athletics
Solid Snake hidden in a box = Blend
Solid Snake avoiding the guards after being notices = Stealth
Solid Snake using the Ketchup Bottle as blood = Bluff
Solid Snake removing the cigarettes from wherever they were hidden = Resolve
Hopefully my interpretative examples help out.