>What I noticed with hour past midnight is increase in damage
>output, landing more hits, and better parrying. Also, it
>looked like skills like disarm and offhand worked more
>consistently. Is this the case?

I think so.

>Or, if we had two human warriors going at with nothing but the
>same exotic weapon, one with the legacy and one without, would
>the one with HPM noticeably win?

I'd assume so.

>The helpfile doesn't mention any specific stats. Is this
>legacy influenced by stats such as int or str?

I don't think so.