So with the dial at 10, the Dark Side is going after their 4th objective for the win. They send Darth Vader, a Probe Droid, and an AT-ST against Luke Skywalker and Redemption. A wild 5-on-5 edge battle ends in a 9-9 draw giving the Light Side the win, but a DS fate card puts a 2nd damage point on the LS objective.

Redemption attacks first and targets Vader. The 2 points of damage sends Vader to the discard pile (already had 2 damage). Now that he is no longer attacking, does this eliminate his card text bonus and remove the bonus blast damage he was providing to the other two DS units?

I say yes, because the unit is destroyed and no longer attacking. If I'm right, it saves the game as the other DS units would only have 1 additional blast damage icon as opposed to 3, leaving the LS objective 2 points short of destruction.

Yes, I'd agree. His effect goes away since he is no longer participating

So I assume that was Navy Vader from Lord Vader's Command ?

A unit's combat icons are only resolved when they are focused to strike (and in the order of their controller's choosing)

It's at this moment that potential bonuses or penalties are calculated and the triggering condition must still be valid.

When either the Droid or AT-ST would have been focused to strike, Darth Vader was no longer in play and thus his effect was no longer active.

You have to pay a lot of attention to such shenanigans because this can be very tricky. I've had the following happening to me: a LS player attacks with Dash Rendar (While this unit is attacking alone, it gains [blast Damage] for each card in the defending player's hand.), accompanied by a one or two drop (of any affilation) while Accross the Anoat Sector ( Each [smugglers and Spies] unit you control gains [blast Damage] while it is attacking alone.) is in play. Wins the Edge Battle, uses their weak unit first to deal unit damage to me. I strike but not enough to destroy Dash. LS player Bamboozles their small unit. Dash is now attacking alone and get +B for Accross the Anoat Sector and +2B for the two cards I had more than they did. Goodbye already damaged objective.