So does any unit with the icon of morr and a morr character or a demigryph mounted character in it.
Terror causing veteran halberdiers (with a demigryph mounted bsb captain carrying the griffin banner) in a grand army is possible. Might as well be greatswords or teutogen guard.
Is it good? Well, it's situational. Not all armies suffer Psychology. But at least it prevents you from testing it without being ItP, and honestly there isn't much in terms of magic banners anyway, so i use the icon of morr every time i got some spare points, even on a core empire knights unit, it's better than nothing, unless you need to save points. Then, terror comes with any fear causing character you can attach, and every fighting character can ride a demigryph.