[jfengel]

It's not at all clearly written. As written it's simply ungrammatical: the comma after "militia" is a syntax error.

Such nitpicking would ordinarily be unimportant, but given that the purpose of the entire prefatory clause is unclear, it completely undercuts any notion that the entire thing is "one of the more clear written" (as the GP said). It makes it impossible to tell whether it's intended to be a limitation or an explanation (which none of the other amendments have or require).

As you say, many of the words are also ambiguous. But for a piece of law whose interpretation is a matter of tens of thousands of deaths per year, one would expect it to at least be grammatically valid.

[tekknik]

How does one person think they know more than the group of people involved in writing it? Your ego is quite strong.

There are no gramatical errors in 2A or any right. None of the terms used are ambiguously defined, try using a legal dictionary instead of saying they’re ambiguous because you don’t understand them.