The way I remember this is that going into warmode as a ghost dropped your stamina, much like running. When your stamina reached 0, you would automatically be kicked into peace mode. Vital change? Maybe not, but it does change the dynamics of macroing healing on ghosts.*Going into War mode while in a ghostly state causes you to "manifest" as a grey figure in the mortal world. Trying to manifest oneself is quite a tiring task for a ghost, so it is no surprise that fatigue sets in very shortly. Once fatigue points are exhausted, your manifestation automatically ends.
Not a big deal, but NPCs should react to ghosts. They would say things like:*Manifestation has been known to strike fear in the hearts of NPCs
"Ahh! Tis a ghost" -- well, not exactly that.. but along those lines.
Huge deal IMO. I dunno' if it was changed during T2A or not, but I do somewhat recall being able to call guards.*GHOSTS CAN CALL GUARDS IN TOWN This can come in handy if you're murdered by a one-shot surprise attack. Ghosts can also ask Town Criers for news.