Had a look round, didnt see this particular info anywhere else, so here goes:
Levelling melee weapons
If you've ever quested in Shadowmoon Valley you've probably met Onorok Torn-Heart (53.92,23.52). Normally at his farm he is surrounded by Domesticated hellboars, which at the moment have a respawn timer of about 15 seconds, and they are yellow, not red.
If you take your melee wep (stave for example) and start attacking one of these hellboars within about 15 yards of onorok, onorok will cast heals on you when you are down at roughly 20% health, and won't let you die (normally, if you try and AoE or tank a lot of mobs, like any healer he cant keep up).
With plain autoattack on you can stand there for ages, just periodically picking up a fresh boar when your last one dies. Onorok himself will also sell food/water/ammo/repairs, so everything you need to farm wep skill is right there.
Levelling ranged weapons
In Netherstorm you will find a mob called Dr.Boom not far from area 52. The only way you can aggro this guy is by going in range of his bombs. Standing at max range, you can auto-shoot/wand him without aggroing him. Dr Boom has a couple of million hp so you can stand there until the cows come home attacking him with no danger to you whatsoever.
(Note: Dr Boom is a quest mob, so you may annoy large quantities of people)
These are the techniques i used for levelling my weapon skills up to their maximum levels, i hope you all find them useful too.