Guild Wars 2

Since you require a number of Balls of Dark Energy for the legendary backpiece, and the only way to get them is to salvage ascended gear, I just wanted to ask you guys, if you have any idea which weapon would be the cheapest or easiest to craft?

I would actually recommend you to do Fractals, if you do the daily and 3 lvl 1-20 fractals you have a good chance of getting an ascended ring. Today for example I obtained two of them in 4 fractal runs. Instead of spending alot of money you spend a bit of time.

and from 40 rings I got zero dark balls then salvage 1 ascended rifle I had laying around poff 1 ball.

Ascended Rings cannot drop Balls of Dark Matter.

As for Ascended weapons, with the recent spike in Spiritwood, crafting something out of Deldrimor would probably be cheaper. A Dagger, perhaps. Alternately, you could craft a single piece of armour, Heavy preferably, which again might be cheaper due to using Damask instead of Spiritwood.

You could also play with RNG and spend Laurels/Badges on Ascended Amulets from World vs. World, and try salvaging those, but you won’t be guaranteed to get a Ball like you are from a weapon or armour.