Easiest way to get all weapons to level 10 apart from the Holosheild Launcher is to play the challenge Endzone which is on the DreadZone Station. In this challenge lots of Claw Tooth Swamers (Blue Swamers) will spawn along with a few Leviathans and Executioners. You just have to stop the enemies reaching the area behind you.
The best way to upgrade the Holosheild launcher is to go onto the Planet Shaar and select the challenge Landstalker Stlkin'. First of all destroy the land stalker that's moving near where you spawn and also destroy the rocket turrets near the land stalker.
You will see a stalker turret blocking your path to the node. Walk towards the stalker turret and have your Holoshield launcher selected and fire it, then stand behind it. Let the stalker turret shoot at the holo shiled until it goes red then fire another. Once you run out of ammo go back to the vendor and rinse and repeat.