This is what I picture Gabriel's armour to look like, except that the red things would be blue instead. I chose it because I wanted something graceful and beautiful, yet functional, and I've never been a fan of angels wearing Roman-style armour like they're so often depicted doing.
Yes, it is actually the Elvish armour from The Lord of the Rings. Sword from the same movies, though I don't know whose sword this was [in the movies].
His sword might be something like this:
... except I like to think there was a stone of some sort set in the pommel, possibly a sapphire, and that it's a little more intricate with regard to things like the hilt, and the runes would be replaced by his name in angelic script. Which happens to be this: