Iron is the Pulling metal, Steel is Pushing. (This is true in artifabrianism, too.)
Spren do have the surges. Even a non-sapient windspren can make things stick together, so they have the Lashings (or at least one of them). Presumably a far more Invested Honorspren could Lash better than a windspren, and an enormously powerful Radiant spren in the Physical Realm could do it better than a "regular" spren ... and Syl, who is now a megaspren like the Stormfather is a demigod figure. (Support: storms in her eyes, as seen by Kaladin.) It won't be obvious even to her until she returns to the Physical.
Note that this makes Kaladin a Fifth Ideal Windrunner, the Herald of Kings, and also a Bondsmith. Resonances, anyone?