I would add a third thing- losing your dice.
I think the thing a lot of people forget about AD&D is that there were some truly fearsome monsters. Some of the worst that people often forget about or overlooked include these five-
Banshee- What? What's so bad about a banshee? Well, the Banshee is outdoors. The Banshee is evil. And the Banshee can wail, and everyone within 30 yards must save vs. magic or DIE.
Ghost- Seriously, in addition to the whole Magic Jar thing, they touch you, and you age 10-40 years. Assuming you make your system shock check. No. Save.
Intellect Devourer- Not just because of the psionic attack (ugh, remember psionics in 1e?). Because they had 6+6 HD, and you needed +3 or higher weapons to damage them, and even then ... they did 1 point of damage on a hit. 1 point. Also, the only spells that would effect them (other than protection from evil to keep them at a distance) were fireball (no damage, would drive them away as bright light), lightning bolt (1 pt of damage per die), death spells (25% chance of success) and
power word kill. A ninth level spell.
Morkoth- Make a save vs. spells at -4 after you enter the lair. Fail, and you are devoured at the leisure of the Morkoth.
Night Hag- In addition to all the other abilities, and they have a lot, they can fire three magic missiles a day for 2-16 damage. And turn ethereal at will. Which means that your party just your spellcaster.