What are these lyrics trying to say?

I think that “young girl in her prime” is talking about girls in their late teens and early twenties, when they are nubile and most fertile – the traditional peak years of fecundity.

“Hold your hammers high” refers (not very subtlely) to erect male penii.

If it means her period, it alluds to the swords staying covered in fresh blood, presumably the blood of your slain foes.

@ragingloli I believe is actually right, this Manowar we are referencing here.

I would say it meant penatrated.
Ie. Penetrated lots of humans, as a young girl in her prime potentially would have been.

Or, because she would have been on heat a lot, been wet a lot, thus may my sword be wet with blood and hungry for its purpose. Bit weird like, but it points to a primal urge and purpose for being. May point more to menstral than to sexual fluid, and or both.