Yep…that sounds like 1st Ed, all right. I used to find the PHB and the DMG fascinating to just browse because you never knew what you were going to read in any particular section. It was frustrating, but strangely charming.
Surely you’d divide up the base XP award, and then the class with the qualifying ability score would receive the bonus, and the other would not.
You’d think so, but I can’t really tell if the authors were thinking that the 10% bonus was something that’s supposed to be applied to the entire XP award.
And don’t call me Shirley.
Alternately, you could divide it based on the way you earned the XP. In early editions, different classes got XP for doing different things: A fighter, for instance, got XP for defeating a monster no matter how it was done, but a thief only got XP from a monster for defeating it using stealth or trickery, and a magic user only got XP for defeating it using magic. The thief and magic-user, meanwhile, could also get XP for overcoming other challenges using their other abilities, which the fighter didn’t.
So your fighter/cleric with 17 Str and 10 Wis would get the 10% bonus when he stood toe-to-toe with a monster and clobbered it with his sword, but would not get the bonus (but would still get ordinary XP) for removing the curse on another party member.
It’s actually quite clear about it. Earned xp is divivded. Whatever percent modifiers apply, apply after the division.
Where does it say to apply the modifiers after the division?
The same place it says you can’t be a character with two classes who’s a Magic-User and an Illusionist. 
also the same spot that says if you try to disbelieve an illusion thats actually a real spell you take full damage with no save.
if I tried to pick up AD&D at my current age I would wonder what kind of crack/meth/mushroom combination the guys writing the rules were on.
Indeed.
If the 1st Edition rules are silent about an issue like this, my only recourse is usually to pick up my SECOND Edition books and look to see if an analogous rule exists.
Of course, this won’t work with things that were deliberately changed between 1st and 2nd Edition, like Bards or Assassins or Monks. (Or with things that were reverted in 2nd Edition to the state they had before Unearthed Arcana, like Paladins.)
… though not even SECOND edition will tell you what the deal is with weapon proficiencies in the case of dual-classed characters. (Can your 2nd class use the weapons your 1st class was proficient with, even if your 2nd class isn’t higher level than your 1st class yet? Do you gain weapon proficiency slots as you level up your 2nd class, before your 2nd class is higher level than your 1st?)
As far as I can remember, the rule was that, if you used a proficiency you gained from your first class while your second class was equal or lower level than your first class, you got zero xp for that adventure. Once your second class got to a higher level than the first,you could use the first classes proficiencies without penalty.
I think you gain weapon proficiencies for your second class at the normal rate for that class.
The restriction was against using any of the abilities of your previous class. Weapon proficiencies are one of the abilities of your previous class. As AD&D rules go, that one seems pretty clear to me (and stupid, but clear).
You’d think so – but wherever weapon proficiencies were discussed in the 1st and 2nd Edition rules, there SEEMED (to my eyes, at least) to be an underlying assumption that weapon proficiencies were character-wide, rather than class-specific.
For example, when discussing Table 34 in the 2nd Edition Player’s Handbook (the table that lays out how many proficiency slots a character begins with and how many levels must be acquired before gaining the next), the text right below the next table said:
“Multi-class characters can use the most beneficial line on Table 34 to determine their initial proficiencies and when they gain new proficiencies.”
This means that every weapon proficiency posessed by a multi-class (NOT dual-class) fighter/thief could be used when performing fighter fuctions AND/OR thief functions. He doesn’t have X weapon proficiencies that he can use only as a fighter and Y weapon proficiencies that he can use only as a thief, he has Z weapon proficiencies that he can use as either. Proficiency with a short sword means he can swing it with a fighter’s THAC0 and backstab with it.
Now, admittedly, this doesn’t touch on the issue of dual-classed characters, which is what we were interested in. But it does highlight the notion that proficiency seems to be “universal” to everything your character can do. And to me, this implies that the player can use a weapon of proficiency even if he gained the proficiency as part of a class that is currently inaccessible to him (e.g. an 8th level fighter changes to a 1st level mage), provided that the new class is capable of wielding the weapon in question at all. E.g., if as a fighter the character gained proficiency with a dagger and a long sword, then he changed classes to a mage, the newly-minted mage would be able to wield a dagger with no penalty, although he wouldn’t be able to use a long sword since Wizard classes can’t use long swords.
The alternative presents its own host of problems. If weapon proficiencies ARE class-specific in a dual-classed character, how many weapon proficiency slots does the new class get when the character first switches? Does a cleric who changes classes to a newly-minted fighter start with 4 weapon proficiency slots, since that’s how many normal Warrior classes start with – or does he gain no weapon proficiency slots until the fighter reaches 4th level (when the next new slot is awarded)? If the latter, how can the fighter possibly survive to 4th level if he has NO weapons he’s proficient with?
Basically, apart from HP, you have to put away everything and start again.
Say you went from Fighter 3 to Mage 1. You have two sets of combat capabilities; those of a third level fighter and those of a first level Mage (including the Mage’s single weapon proficiency). If you wish to earn xp you must employ only those capabilities a Mage would have. You’re likely to be a little harder to kill since you have more hit points, of course.
It seems clear enough to me.
A multi-class fighter/thief doesn’t have one set of proficiencies when he’s acting as a fighter and another when he’s acting as a thief, because he never acts as a fighter or as a thief. He’s always both.
In that case, when your 3rd level fighter changes to a 1st level mage, will the mage get his own new proficiency slot (because 1st level mages are supposed to start with 1 weapon of proficiency)?
Or do weapon proficiency slots work like hit dice, where the mage won’t start earning any new ones until he surpasses his old level as a fighter?
I thought it quite clear the answer was yes.
They are not allowed to pick up a weapon they have proficiency in as a Fighter without losing all xp for that adventure. What are they going to fight with if they don’t get Mage weapons?
They’re allowed to pick up the weapon, and even to use it, just not to use it proficiently. A fighter who’s just dual-classed to mage could pick up a longsword and deliberately choose to accept the massive nonproficiency penalty, and gain xp normally.
Of course, if you took dagger proficiency as a fighter, then dual classed to magic user, you suddenly forget how to use the dagger. Or relearn how to use it as a magic user. Then, when you have sufficiently leveled up as a magic user, you suddenly remember how to use that dagger as a fighter.
No, you never forget about it. However, you can’t use it without losing earned xp for that adventure. if you develop the skill as a wizard, you no longer suffer that penalty.