It's the heavy chorusing of the solid state amps on the album. Gallien Krueger amps are INCREDIBLY specific. Some say that you can get close by adding a chorus over distortion of a tube amp... Not even close.
Recently, I purchased a Kemper Stage and found a Gallien Krueger 250 ML profile and I gotta say, it sounds so different than everything else. Not having tubes, makes it somehow less volotile and more controlable. And that is exactly what the intro of Wasted Years is. Heavy chorus, integrated delay and slight muting with the right hand.
Also, Maiden or not, that GK sound is incredibly useful specific things. I'm planning to use it on Purple Rain's solo with a cover band that I'm in, as it just fits the vibe.
So in short, it's the amp and there is absolutely no synths on Wasted Years. There is also a neat trick done by Dave in studio. He played an arpeggiated Csus2 chord during choruses (the chord at the end of each chorus verse), which gives it some synth-like quality, but it's just guitar.