The manual for the original Wizardry has some lies in it. Here are some things the manual gets wrong:
1. IQ and Piety don't affect your ability to cast or resist spells; they only affect your chance of learning spells.
2. Agility does not help you avoid attacks. (It does help with inspecting, but not disarming, treasure chest traps.)
3. The manual states that cursed items are not always bad. This is not the case in Wizardry 1. (The first useful cursed item didn't appear until Wizardry 4.)
4. The manual claims that Wizardry is a non-sexist game. However, there is one case where the game uses a male pronoun to refer to a character: If a character casts (MA)HAMAN and forgets spells as a result (did you know this could happen?), the message will use a male pronoun. (Note that this rare side-effect, I believe, was removed in Wizardry 2.)

He he, that's funny.

Actually there is no sex/gender in Wizardry 1, but when you sell an item at the Boltac's Trading Post he says *ANYTHING ELSE, NOBLE SIR?*,so the game suggests that all adventurers are men.

You are missing the line I was referring to:
"BUT HIS SPELL BOOKS ARE MANGLED!"

This has a 1 in (level) chance of happening anytime (MA)HAMAN is cast, so it's rare. (The game actually compares the random number to see if it's equal to 5, which is a rather strange way of doing this.) Given that not that many players use this spell because of the level cost (especially in Wizardry 1, where it isn't that useful), most players never see this line and are not aware that this can happen.

Incidentally, when this happens, every spell the character knows has a 50% chance of being erased from the character's spellbook.

This possible side effect was removed in Wizardry 2.

As I said, even if you did cast it, you probably wouldn't see this side effect. In any case, that spell isn't that useful because you don't get any control over what it does.

It's worth noting, however, that in the Apple 2 version, MAHAMAN has a 1 in 3 chance of killing the enemies outright, causing you to win the battle. (Works even on the final boss!)

By the way, which version are you playing?

I'm playing 1984 IBM PC version. (I googled to be sure and whooo there are so many different versions)