Magic Swords, Proficiencies, and the 1e DMG

This is actually like three short posts about magic swords rolled in to one.

• I've been thinking about trying to organize some in-person D&D, and OSE is probably an easier sell than ACKS in this part of the world.  So in the absence of proficiencies, my previous post about magic items in place of proficiencies has been back on my mind.
  
• If I also wanted to keep cleaving in an otherwise mostly-stock B/X game to give fighters some of their OD&D multi-attack mojo back and help them scale into the high levels, that might also be a good thing to attach to magic swords.  At first wag, something like three cleaves per round per point of bonus seems likely to keep pace with 1 cleave per HD at least up to name level.  This has a number of other interesting properties:
• Fighters and thieves almost certainly get cleaves sooner than clerics as a consequence of the treasure tables being magic-sword-heavy.
• Non-champion low-HD humanoids are unlikely to cleave.  Might want to grant bigger monsters some inherent cleaves, much like how they have magic weapons for the purpose of damaging other invulnerable monsters.
• This also creates an interesting qualitative distinction between "mooks who could easily be humans in rubber masks" and "supernatural monsters who can kill everyone in a mead hall in a couple rounds".
  
• Mid-level rival NPC parties with magic weapons are cleave threats.
• On the downside, antithetical to "Steel isn't strong, boy.  Flesh is stronger...  What is steel compared to the hand that wields it?"
  
• Second, there was a discussion in discord recently about sentient swords.  Thinking about magic swords through the lens of "class proficiencies for fighters and thieves that clerics and MUs don't get", sentient swords are actually a restricted form of spellcasting for non-caster classes.  I think they're really important, that using them should generally not be a hassle, and neglecting to roll for them is a contributing factor to caster superiority.  The whole ego / conflict of wills mechanic is to keep high-level powers out of the hands of low-level fighters, and to keep fighters from amassing too many spell-like abilities by having multiple sentient swords. 
• I've been skimming the 1e AD&D DMG recently, because it also keeps coming up in various discussions.  I went and looked in the treasure tables because I was curious about how it handled sentient swords, and several things struck me:
• 25% of swords are "unusual" (sentient).  This is in the same ballpark as B/X's 30%, but much higher than ACKS or later editions.
• "All abilities function only when the sword is held, drawn, and the possessor is concentrating on the desired result."  This isn't "ask the sword nicely to use its powers".
  
• AD&D computes willpower score differently - sum of a character's Int and Wis scores plus their level (with the level bonus reduced by damage taken).  This means that cap for character willpower/personality score is basically unbounded!
  
• A "typical" random sentient sword has about 13 Int, empathic communication, two detection abilities and an Ego of 3 or so, and is reasonably useable even by a low-level fighter of average mental stats.
• "N.B. Most players will be unwilling to play swords with personalities as the personalities dictate. It is incumbent upon the DM to ensure that the role of the sword is played to the hilt"
• har har
  
• Reading the 1e DMG's magic swords, I was also struck how a number of them had effects that activate on a natural 20.
• This wraps back around to limiting the scope of proficiency-like exceptional cases by making them magic items.  Rather than taking Weapon Focus in order to get the ability to crit, it's a property of some swords.
  
• Making crits a property of magic weapons means monsters aren't critting PCs, which is the usual trouble with critical hit rules.  Except for that tiny subset of monsters with eg Swallow Whole abilities that trigger on a 20 - it's probably OK to have it as an exception for, again, big scary supernatural monsters.
  
• It also means you can have a variety of critical hit special effects, like vorpal's save-or-die vs the sword of life stealing's level drain on crit, without needing a complex critical hits table or system.  These effects can also be quite fantastical, since they're magical in origin.
• This might also be a reasonable way to handle combat-maneuver like effects.  Magic hammers that sunder weapons on a natural 20, axes that break shields, rapier of disarming, magic shield that knocks foes down when they nat 1 against you, ...
• Magic swords might also be a reasonable way to sneak backstab multiplier scaling into B/X, where even a max-level thief only does x2 damage.  idk whether I'd want to make just particular backstabbing swords that boost it, or something as simple as "a thief backstabbing with a sword +1 multiplies the die roll by x3 instead of x2, +2 -> x4, +3 -> x5".