Jonathan and Saul Trust in the Lord and God Gives Them the Victory

There's a deliberate contrast set up here between Jonathan and Saul that again we're supposed to observe. The Septuagint doesn't say bring the Ark, it says bring the Ephod. It seems kind of odd given where we last saw the Ark in Karyath Yereem and Baal Yudah. So what's going on here?