I will be changing a few of the multi-class titles though I'm a bit mixed on what direction to take it. The titles are similar to normal class titles (Veteran, Cutpurse, Wizard, etc) in that they are mostly for fluff with perhaps a minor ability to adhere the two classes better. I'm deciding on wither to make it very setting specific or use more intuitive titles.
Example, a Fighter-Cleric would be a Paladin. Pretty intuitive. Setting specific would be something like a Dwarven Fighter-Cleric would be a Whitebeard. Not so intuitive but perhaps a better choice since this sort of multi-class fluff is well outside of the realm of B/X anyhow. The main problem is the setting specifics titles would indeed be rather specific, slanting towards race with specific classes.
I've been reading up a bit on what Gygax had in mind for 2nd edition AD&D and here are the classes that seemed to be included Cavalier, Barbarian, Acrobat, Mountebank, Savant, Mystic, and Jester. The first three were in Unearthed Arcana of course. Savant and Mystic seem fairly similar, both being based on divination (a DMs nightmare). The Jester is not really for me, but I am sure some others would get some use out of it. Bards were to be revamped, Monk would removed and put into Oriental Adventures. The one that interested me the most is the Mountebank because I never heard of it, and because it seems fairly interesting.
The Mountebank is a bit of a a skilled liar, heavy with slight of hand and verbal trickery. They would depend a lot on speed, theatrics and disguise. From what I read Gygax had them in mind as primarily a Thief with a bit of Illusionist and Fighter. Judging by Unearthed Arcana they probably would have had a plethora of specialized abilities, their own theify skills and probably their own spell list too. Naturally I won't get that far into since this is B/X, but I will add the title to for a PC who fits the bill.
Monk I will probably remove and replace with Mystic or perhaps something else. This will be the 'Fighter-Mage' although I am not sure how the mechanics will go. This one is a bit tough because of the balance. I may allow any weapon but still disallow armor for spell casting, or something of the like. Bishop I do not care for overly, but I will probably leave it in as a homage to Wizardry. If that is the case then I will need to develop a strong clergy that would at least resemble something abbots, bishops and whatnot would be involved with. Stratogineer is just a placeholder name but I have yet to think of replacement. I do want a Dwarf title somewhere that will involve mechanical things.
The rest I will probably leave in and stick a fork in it. At the moment it will look something like this.
Fighter/Cleric - Paladin
Fighter/Mage - Mystic
Fighter/Thief - Ranger
Mage/Cleric - Bishop
Mage/Thief - Illusionist
Cleric/Thief - Assassin
Fighter/Thief/Mage - Mountebank
Elf (T/M/C) - Druid
Dwarf (F/M/T) - Stratogineer
Halfling (F/M/T) - Sheriff
Human (F/M/T/C)- Bard
Paladin - Zealous and self-righteous, the Paladin smites his foes with the holy might and clarity of purpose. Valorous and bold, the Paladin is is both a slave and a master of his Lawful nature.
Req : Lawful, Charisma 12
Abilities : Paladins may re-roll a failed save throw once.
Mystic - Mystic warrior who study with forbidden masters and ancient warschools occasionally return more than they once were. Unpredictable and aloof, Monks are both rare and unsettling, never quite at home away from the isolated training grounds they left.
Req: Wisdom 12
Abilities: Mystics may use any weapon and still cast spells.
Ranger - Often seen as well trained brigands, Rangers are masters of the wilderness, striding with ease where others loose their footing.
Req: Int 12
Abilities: Ranger may use ranged weapons for their backstab ability.
Bishop - Unbeholden to the influence of the traditional Clergy, Bishops wander the lands setting their own holy agenda collecting lore and reason in the world.
Abilities: Bishops may attempt to identify the nature of magical or supernatural effects; this includes items, spells, phenomena, as well as flora and fauna.
Illusionist - Pragmatic tricksters who use magic and shadows to beguile both friends and foes. They are both the joker and the joked upon, as 'true' Wizards discount their petty ways as demeaning.
Abilities: May cast spells listed with a * on their Magic User spells list (Illusionist spells).
Assassin - A super human fighting machine, the assassin is gifted as a spy, a saboteur and a killer. Universally loathed and desired, assassins walk a fine line between life and death.
Req : Non-Lawful, Strength 12
Ability: Victims of a successful Assassin backstab must make a save throw vs Death or immediately die.
Mountebank - Charlatan skilled with his hands as well as a his rhetoric; the Mountebank is a liar, a thief, and trickster. They use speed, theatrics and disguise to accomplish what a mere blade can not .
Req: Charisma 12, Dexterity 12
Abilities: If a Mountebank hold the attention of a humanoid(s) for more than 1 turn, he may Confuse them (as spell).
Druid - Druids are the keepers of natural lore and the order of the seasons. Compelled to travel to see the world, Druids yearn to wander the years in a new location every day.
Req: Wis 14
Ability: Druids can change their shape to any animal their size or smaller.
Stratogineer - Powerful and possessive, the Stratogineer of the deep workshops hold the might of sway of the cog, gears and steam at thier grasp. Bowing to no one man but to the power of the mechanical alone, Stratogineers tread heavily upon the world in their bronze-tubed boots.
Req: Int 14
Ability: Stratogineers can mechanically replicate any spell they know with mechanical devices.
Sheriff- The Halfling Sheriff is prophet, divining the future and setting upon the world to correct and thwart the horrors set in his mind's vision. Ultimately a protector of the Halfling people and the world, the Sheriff takes upon the role of prophet and corrector.
Req: Wis 14
Ability: Sheriffs presence may be called upon at will, once per day.
Bard - Both whimsical entertainer and traveling sage, Bards use dance and music to soothe those around them. Known as true polymaths, Bards seems to have knowledge in just about everything.
Req: Cha 14
Ability: Any intelligent creature listening to the Bards song for a turn or longer will be inflicted by a Charm as the spell if the bard so wishes. Save throw applies.