A paragraph break is appropriate here (so Revised Standard Version).

When the battle became fierce may be expressed as “When they were fighting each other fiercely.”

There appeared to the enemy from heaven five resplendent men on horses with golden bridles, and they were leading the Jews: Good News Bible has lost the idea that the five beings appeared from heaven, which is better rendered “out of the sky.” The Greek word for resplendent means magnificent, awe-inspiring. For resplendent men, Good News Bible has “handsome men,” but it is better rendered “magnificent human figures” (similarly New English Bible, Revised English Bible) or “magnificent human beings” (similarly Tedesche). Placing the adjective “magnificent” with the word “men” in English turns the phrase into a description of men who are handsome and physically appealing. The models below use “human figures,” but translators who can describe the scene properly with “men” should certainly do so. For bridles see the comments on 2Macc 3.25.

Here are alternative models for this verse:

• When the fighting was at its heaviest [or, worst], the enemy saw five magnificent human figures coming down from the sky on horses with gold bridles, and leading the Jews [in battle].

• When the Jews and Timothy’s soldiers were fighting each other very fiercely, the enemy soldiers saw five magnificent human figures on horses with gold bridles suddenly come down from the sky and lead the Jews in battle.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on 1-2 Maccabees. (UBS Helps for Translators). New York: UBS, 2011. For this and other handbooks for translators see here.