Aside from at the Adventurers Mart, is there anywhere else in the game where it is possible to get a second one?

I'm running a solo game, and I've come up against a brick wall against the Emphatic Manifestation because I've not got any way of healing it.

Thanks in advance.

Hmm, are you doing the Quest after Spellhold, or what?

You can get one in Mekrath`s lair.

A cure light wounds (Bhaalspawn ability) is enough for the manifestation...
I dont't know about evil/neutral characters, but the good ones do have this ability. But IIRC, my LE monk had it, too.

There is one in Mekrath's Lair as mentioned above.
You can always use a scroll of restoration available at any temple. It is usable by all classes (IIRC) and far more abundant than RoR. However that would require resting afterwards. Other possibilities would include the Staff of Curing and Scrolls of Cure Serious Wounds, but that would be for rogues with UAI only.