After a few hours of study, and because of the symbol is weapon themed, you find in a book depicting battle standards the symbol you are looking for. At least, it is the same basic symbol, but cleaner. Something that would definitely look good on a flag, or shield, or breastplate. The meaning is obvious, "Apart we break, together we prevail" or similar. It can be interpreted other ways too, after all, an arrow in a quiver isn't of much use if it is never drawn. Arrows are made to be used up. Some would say the same of soldiers.

In any case, this standard was held by a commander from the distant past. He gained and lost many cities in conquest. It is written he slew thousands with the stroke of his wand. After a successful campaign near the Spine of the World, he disappeared. Some say he took his armies north and either died on conquered in the frozen wastes. Or became part of the Northern Tribes. Or that he was assassinated. Or that he simply fell ill. But the accounts agree that his reign of terror in the Sword Coast region ended abruptly.

He was called The Dreaded Korosk. There is no mention of the symbol being used as a holy symbol. The banners were pulled down almost as quickly as they were erected, then forgotten to time.

Fergan, after seeing the emblem, says telepathically: "We are in danger, here. I know that sign."