Make me a knockback/knockdown/launch build
I can’t exactly say I’m an expert (only been playing gw2 for 2 months) but if I may, I could outline some ideas.
Firstly, to complement all the stuns and knockdowns and stuff, I’d say you should definitely use Lightning Rod (Grandmaster air trait) for extra damage, 50% fumble and -50% endurance regeneration.
For the weapon, I’d probably go with the staff. While the focus and dagger do have some attacks with disabling effects, I find the staff to be more reliable with static field, gust and unsteady ground. Unsteady ground knocks back foes who try to cross so if you time it right you can get one or two of those lightning strikes in. I also enjoy using static field and then gust to knock the enemy back in to the edge of the field for a double (or even triple) strike.
If you use the staff you should also use Aeromancer’s training (2nd tier air trait) which reduces the cooldown of static field and gust pretty significantly. This also puts those two skills on a lower cooldown than ‘Updraft’ (offhand dagger), ‘Earthquake’ (offhand dagger), ‘Comet’ (focus) and ‘Gale’ (focus). Comet only has a 1.75 second lower cooldown than static field at 26.75 seconds with aeromancer’s training.
You could replace aeromancer’s training with the shocking aura trait on the same tier but using a staff, I don’t really think it’s very useful when it’s so important that you keep some range. It does however give you an extra 20% damage against disabled targets so if you think you can pull it off, try it out.
Then you also have tornado. You should use the 3rd skill while in tornado form since it has knockback and gives you some lovely lightning strikes. If you can set up a static field or unsteady ground just before you transform and use your rocks to push your opponent in to them then you can get some pretty great damage. Tornado is also now a cantrip; a fact you can exploit by using the 2nd tier water trait: Soothing Disruption.
I should also mention that you could instead use the elemental glyph in air attunement since your elemental can stun your opponent.
Another option you can use in your utility is the lightning hammer. It has a launch and a self-centred static field but I haven’t really tested it out so I can’t say with any real certainty that it’s a good or bad option. Unfortunately, it’s the only non-racial disabling utility there is (as far as I know).
Hope I helped. Have fun.