[wisty]

Or it means that if the government needs to call in levies, it would be good if the volunteers could show up with appropriate weapons. Ironically an automatic rifle (think an AK) could be what they're talking about, while pistols (being arguably useless side-arms in a battlefield) might be far less in the spirit of the law.

Historically, not owning a sword or longbow could get you in legal trouble in some cities and time periods, since it meant you weren't capable of helping defend the city. I'd say that in the spirit of the law, it should mostly allow the ownership of useful infantry weapons, or dual purpose ones (hunting rifles?), rather than self defence pistols.

But the US interprets it differently because the constitution is a bit vague, the constitution is hard to change, and practicalities and politics exist.