This line seems to contradict what Draco is saying and conflicts somewhat with the MM entry for Immune. Let's take out the part about Resistance because the "or" means it should still be logically valid
A contradiction means a situation where two premises taken in concert prove to be impossible. My interpretation is -far- from impossible, in fact, I've named two examples where it applies without houseruling that Keywords do not apply to the entire power. (which itself is contradicting the PHB) As far as I can tell, my interpretation is the only one what does not contradict all applicable rules.
A power with Foo Keyword is a Foo Power and has Foo Effects. That doesn't mean that every damage it deals is foo damage (damage types and keywords are different, if related, animals.) A Fire power can deal non-fire damage, for example. That doesn't make it a non-Fire effect.
Also, what of this hypothetical power:
Minor Weird Wizard Attack 1
Channeling your target's worst fears, you attack him with the essense of his own nightmare.
Encounter - Arcane, Fear, Implement, Psychic
Standard Action, Close Blast 3
Target: Every creature in blast
Attack: Intellegence vs Will
Hit: Target takes 1d10+Intellegence psychic damage.
The flavor of the power is that you attack him with his own fear. But, there's no non-damage component to plant down as the 'fear' part. So, under your interpretation this is a fear power with no fear effect. Under my interpretation, it's a fear power and gives a fear effect.
The simple fact is, there exists powers where specific effects have keywords other than the entire power. (Again, look at the Warden level 1 Dailies for proof) Thusly, it is reasonable to conclude that when the RAI that a power will have different keywords for different parts of a power, it will be explicitly written.
Also, according to PHBII, 'Encounter' is no longer a Keyword, it's a Usage.