"Honourable", as used in the context of paladins, samurai etc doesn't simply mean "recipient of honour bestowed by friends/family/clansfolk/etc". It characterises a particular set of dispositions and commitments that can be somewhat generalised over a whole range of non-liberal cultures. A good discussion can be found in M I Finley's The World of Odysseus. The same sorts of idea can be found in Icelandic law codes, which define "murder" more as we would tend to define "assassination" ie killing someone in their sleep, in a dark alley at night, with poison, etc. Killing someone in open combat wasn't murder. (Even in the 19th century a range of North American and European societies had practical difficulty bringing duelling within the scope of the law of murder - the change in this respect can be seen as a triumph of enlightenment liberal values over the value of honour.)
To be honourable, in this context, is to recognise the standing and esteem of others, to evince in one's own action a due self-regard as well as other-regard (eg not being snivelling, not being a coward etc), keeping one's words, offering wine to one's guests, etc, etc.
If honour has to be put into the 9-point framework (not a completely trivial matter) it fairly obviously, to my mind, correlates with law. Besides the obvious textual point in 3E (that [MENTION=16726]jsaving[/MENTION] pointed out), there is the fact that paladins, samurai, monks etc have always had to be lawful, and that feckless types like barbarians and bards are often prohibited from being lawful.
To reiterate a theme of mine in this thread, I think there are tensions between defining law in terms of honour (which is a pre-liberal notion) and then defining good in terms of well-being, dignity etc (which is a liberal, enlightenment, human rights-y notion). It puts pressure on paladins to be played as a combination of Lancelot and Amnesty International, a pretty unstable combination (and the cause of many a paladin debate for more than 40 years!).
