Does the legend count when you control something empowered?

Yes — for Shock Blast's "This costs [2] less if you control something that's [Empowered]," your own Empowered legend counts.

You control your own Champion Legend (Rule 191.1; FAQ #11765 confirms this explicitly), and legends can carry the Empowered status just like units and gear — Matriarch of War and Soul's Reflection become Empowered off "when you empower something else," and Rogue Assassin, Defender of Tomorrow and Boy Who Shattered Time have Empower themselves. Shock Blast says "something," not "a unit" or "a permanent," so any object you control with the Empowered status satisfies it, including a legend. The discount applies when you play the spell, so the legend has to already be Empowered at that moment.

One caveat: if a card asks for "an Empowered unit" or "an Empowered permanent," the legend does not count — legends are expressly not permanents and not units (Rule 175). It works here only because Shock Blast's wording is deliberately broad.