Guess I'm just too old school. Played DnD in college (AD&D rules). At that time, heal/harm was the top of the cleric's healing skills, and clerics only had up to 7th level spells. Some DM's treated the use of cause spells (the reverse of the healing arts) as an evil act, and good clerics weren't allowed to use them. It was a touch spell that in the good old days meant you actually had to hit the thing.
With the new rules came 8th & 9th level spells for clerics, but heal was left at 6th. Add to it the rules about how touch attacks don't factor in the armor etc of the creature and you have a overpowered skill. In NWN, it has all the appearance of being a ranged touch attack. That is, I've seen the cleric henchman stand back and cast harm on the creature. This just further empowers the spell.
This is nothing against NWN. They were implementing the DnD rule set. But it is, IMO, an overpowered spell for it's level. I agree use whatever the game provides, the belt is another example. 30K for a overpowered item is something you either take advantage of or not. I personally chose not to use harm, nor do I buy the belt.
I apologize if I came across a bit strong on the "cheap trick" crack. My son uses it a lot and says how dragons are soooo easy. Yeah, well dropping the any creature to 1-4 hps just by touching with like a 75% chance to hit doesn't take much. With the lack of a real AI for the dragon, and lack of flight, dragons are too easy in NWN. He's learned that in a pen&paper DnD game, dragons are to be feared, and not triffle with.