The suit has weaknesses.
Mainly, the smaller an object is, the weaker the defense.
And it wouldn't have stopped Superman from, say, trapping Slade. His super breath ice is strong enough to hold Bizarro Superman and New Krypton Kryptonians.
Or he could have dropped him in a pit as deep as the grand canyon. Or tried a super whistle/shout.
He just fought like an idiot.