My personal preference is that all voices in a work are to be written from an in-universe perspective, and that includes the voice of an omniscient third person narrator. While I understand that using modern equivalents in analogies can be preferable since it's easier to form an image with a familiar equivalent to reference from, I personally find it incredibly jarring when a sudden real-world reference is made.
So I do my best to simply describe it e.g. a "batter's stance" would be "so-and-so hefts the weapon over one shoulder, grasping the hilt/shaft/haft with both hands, feet spaced somewhat apart in preparation for a mighty swing" or some such nonsense. I'll completely admit that it's not very concise and can potentially be confusing to readers, but I prefer it that way.
So I do my best to simply describe it e.g. a "batter's stance" would be "so-and-so hefts the weapon over one shoulder, grasping the hilt/shaft/haft with both hands, feet spaced somewhat apart in preparation for a mighty swing" or some such nonsense. I'll completely admit that it's not very concise and can potentially be confusing to readers, but I prefer it that way.
