Interesting question,
alatar! *rolls up philologic sleeves*
The first thing that comes to my mind is rhythm. Consider
Quote:
I have had a HARD life and a LONG
|
versus
Quote:
I have had a HARD and LONG life
|
(
X for primary stress,
x for secondary stress).
The first version just 'rolls' better in my ear - the length and hardness both are stressed duly without the stresses getting cramped, if you see (or rather hear) what I mean. I'm sure the Prof, like any great writer, paid close attention to such things as the rhythm of his sentences - as evidenced e.g. in Tom Bombadil's dialogue, which is for whole paragraphs in the same metre as his verse, just printed as prose.
Another aspect - I think Aragorn (or Tolkien) didn't just mean that his life was a) hard, and b) long, without the two qualities having anything closer to do with each other. Rather, he says:
"I have a
hard life
[get that, Boromir, you're not the only one who's been fighting the Shadow]
and a
long
[so I've been doing that for a while longer than you]."
Long gets the final stress, but it's enhanced by the preceding
hard which qualifies it - meaning he hasn't just led any long life, but a hard long life, a long life full of hardship; and the rhythm, with its two carefully placed stresses, hammers the point home.
(I just lurve close reading, in case you haven't noticed.

)