Power
Depending on the kind of materials science you do, you'll know all there is to know about power. Like, how to build more efficient lithium-ion batteries. Or create better low-cost fabrication strategies for photovoltaic power.
Oh, wait. Sorry. You were asking about a different kind of power?
Yeah, you'll have some of that. Power and responsibility—you'll have a healthy dose of each. Power, because materials engineers tend to be respected, highly-valued members of their companies.
If a cosmetic company wants to create a new line of Edward Cullen-inspired diamond powder, guess who they need on tap? And if said diamond powder turns out to cause skin rashes, guess who they'll need to figure out what went wrong? For that reason, you're trusted with—and responsible for—creating high-quality, safe products.
But in general, engineers are team players, and materials engineers are no exception. Any power you have, you'll share with the rest of your team who helped make your cool new discovery possible.