There is always a simple way of answering this - what did Gary/the DMG say?
The obvious examples of things with intelligence are artifacts;
- Baba Yaga's hut has an intelligence score. Of course, it is an evil tardis with giant chicken legs, so... why not be smart, too?
- The Orbs of Dragonkind each have an intelligence score and an ego score and can struggle with their wielders just like swords!
OK, so that seems to show that not just swords can be smart!
What's that? Did someone say "yeah, but those are artifacts so they don't count"?
Well, I have heard that before - that artifacts and relics are so 'other' that you can't treat them as examples. I don't agree with it, but I will admit it has merit, so let's keep looking.
How about the Figurine of Wondrous Power - Onyx Dog? It has an intelligence of 8-10 and can speak Common. This seems to imply it is much more than the spirit or intelligence of a dog. [Well, unless all it can say is "I love you"]
Quick Aside: Can you see it now? An adventuring party of 4 - a paladin named Frederick, Dymphna the low-Int cleric, Vell'Ma the mage, and Norville the Shaggy, the thief. Norville has an onyx dog that says things like 'ruh-roh, raggy, a rombie!'.Anyway; the onyx dog looks fairly clever, although it isn't as smart as a dim sword. No mention of an ego, so let's keep looking.
Then we get to Appendix H. I love appendix H because it implies so much! Gary tells us, rather casually, to simply take a few things from 'features' and a few things from 'attributes', randomly toss them together,and turn them into tricks.
Why do I mention implications and stress how casual Gary was? Because Appendix H tells us, pretty clearly, that anything can have intelligence. From a pool of water to a machine to an illusion to FIRE - anything can be smart. Anything can have an intelligence score and, it is strongly implied, any smart thing has an alignment.
Let's start with the obvious stuff, first.
Intelligent daggers and staves shouldn't be a big stretch from swords. A dagger that can make its wielder Invisible once a day and can detect precious metals within 30' at will would be pretty valuable to a thief. A Robe of Eyes with its own intelligence could warn its wearer of creatures approaching while she slept. A smart Instant Fortress could act as its very own doorman, admitting people it knew without the owner being present.
All pretty cool.
But since this is obviously possible and obviously handy, why is it only really directly mentioned (and turned into a table) for swords? And why is it done for swords so often (after all, intelligent swords are almost 3% of all magic items)?
Let's talk about magic item restrictions for a second..
In 1e certain types of magic items are only usable by certain classes or class groups - a fighter can't use a Wand of Fire; a magic-user can't use Gauntlets of Swimming and Climbing, etc. This seems to imply that there is more than just power words or even force of will involved in activating certain magical items - there must be some sort of 'essence' associated with these items and their powers.
Fighters seem to be the most restricted in this regard (I haven't done a real examination, this is just an impression). And many, of not most (or even all) of the powers seen in intelligent swords appear to be the sorts of powers a fighter could not use if the power was in, say, a wand.
Here's my theory: the reason for the prevalence of intelligent swords is because the sword's intelligence is required to make the powers of the sword usable by a fighter. The intelligence of the sword is a form of proxy - since the fighter can't activate the sword's powers directly he, in the end, orders the sword to activate the power for him. The intelligence is, in a very real way, a workaround for the limitations faced by a fighter using a magical device.
That seems to make sense for the powers that seem to mimic racial abilities, too. A human is never going to be able to use dwarven racial abilities. But a dwarven-forged sword with an intelligence could invoke those racial abilities on behalf of a human wielder.
Suddenly intelligent swords with special magical powers make a lot more sense, don't they? And the fact that intelligent swords are the one thing really covered in any depth make more sense, too.
Next: Part II