You'll recall that a few days ago, Joshua Myerson asked about expressions such as "short sleeve(d)" & "large size(d)". I put it to Rodney Huddleston who pointed me to p. 1709 in the Cambridge Grammar of the English Language. There you will find a rather ingenious solution: the -ed suffix is not the same -ed suffix you find on verbs (cf. the -er suffix on nouns vs. the -er suffix on adjectives). Not only that, the suffix does not apply solely to the final word of the pair, but to the pair as a unit. In this way, it is similar to the possessive suffix on somebody else's, where else's all by itself makes no sense. Though this -ed usually applies to modifier-noun pairs, it can apply to individual nouns (e.g., bearded). The basic meaning is just with (though other specialised meanings also exist).
Given this analysis, we don't have to worry about adjectives modifying verbs any more. This leads to the interesting distinction between high-powered tools in which it wouldn't make sense to ask "by what" and powered tools in which it would.