Sentence structure of second amendment

Wikipedia mentions two versions.

As passed by the Congress and preserved in the National Archives:

A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.

As ratified by the States and authenticated by Thomas Jefferson, then-Secretary of State:

A well regulated militia being necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed.

The first version seems grammatically awkward to me. Isn't there something wrong in the sentence?

Just to get this off the unanswered list.

Back when the US Constitution was written, it was fairly common to separate a subject from its verb with a comma if the subject was even somewhat long or complex. For example:

The river behind the field next to my parents’ house, flows fast.

This also extended to gerund phrases:

The only barber in the whole of San Antonio worth going to, being Mr. Jessup’s, I shouldn’t bother visiting any other parlour.

Of course, in current English, both these sentences would be considered highly mispunctuated, and woe betide any student who punctuates like this—their English teacher would be reaching for the #5 red pen to tear them a new one, as they say.

It is interesting to note that this style of punctuation had apparently (if we are to judge by this example alone) fallen out of favour already by the time of Thomas Jefferson, since the ratified version has perfectly standard, current punctuation with no commas separating subject from verb.

Note: The actual question here, of whether there is not something grammatically awkward in the original, must be answered in the negative. This is purely a matter of punctuation; grammar does not come into it at all.