I've been camping these for the last 2 days and there are 2 different kinds ones that are Heros and the others are heros. The difference is that the Hero doesn't run when low on health and also drops spectral parchments (I've collected 2 in about 30 kills). The hero gets scared and runs when low on health and drops vendor trash (if anything). Well Good Luck and Good Hunting to all!!!
I've noticed that these, unlike their counterparts will also run when low health. I've found this useful when breaking charm on a hasted pet. Rather than having to run some and root. The disadvantage is their lower damage / hp.
Drops the standard vendor stuff, soldiers notebook and pieces of armor and weapons that are unequippable. Only the sentries drop spectrals it seems. But on the other hand these unlike sentries can be snared and rooted.