Also recall the disagreements that the Fallen had among themselves.
The deceiver might not have been the Watchers only enemy-perhaps Soulblighter hated him for some reason as well. And he could have been there to either thwart Bahl'al's efforts, or even just to beat him to the codex. Soulblighter on his own works MUCH faster than a whole force, and by not bringing troops he prevented actually warring wtih the Watcher.
Also, recall Myth 2. Alric brings back the deceiver, for obvious reasons. Soublighter brought back Shiver. Lets assume that Connacht/Balor can't be brought back, and we know too little of the other fallen to theorize on them. Why was The Watcher never resurrected?
Alric wouldn't have brought him back-he would have been a fool too. While the deciever was a shady character, at the least, he had also once been a strong force for the light and could be persuaded to make a return, if only temporary. The Watcher, on the other hand, was an ancient evil and would have almost indefinitely re-waged war on Muirthemne.
And we know soulblighter could resurrect past fallen, since he resurrected Ravanna. Why didn't he resurrect the Watcher? Because he was unsure the Watcher would side with him. Because he had had problems with him in the past.
