[the phantom]

I generally look at strength as strictly physical power, and everyone knows that it takes a lot more than big biceps to take down Sauron, otherwise any decent warrior such as Eomer could do it. I think that strength is a component of power.

I would say it this way; it takes power, not just strength, to supplant Sauron. A decent way to gauge power would be combining the following- the amount of knowledge you have, strong control over your own will, the ability to master others' will, amount of skills and how advanced they are, mastery over matter, and ability in battle.

That's my definition of power anyway, and I think that Elrond would have to be ahead in the power department for Tolkien to say what he did.