David, Negeri Sembilan on Malay Peninsula actually has very strong Minang roots.
Some quotes from Newbold, 1839:
"The inhabitants of the states in the interior of the southerly part of the Malayan peninsula, particularly those of Sungie ujong, or Simujong, Rumbowe, Johole, and Srimenanti, derive their origin from the parent empire of Menangkabowe, in Sumatra, more directly than the natives of the neighbouring states."
"Sir S. Raffles, in a letter to Mr. Marsden, thus notices the state of Rumbowe: "Inland of Malacca, about sixty miles, is situated the Malay kingdom of Rumbowe, whose Sultan, and all the principal officers of state, hold their authority immediately from Menangkabowe, and have written commissions for their respective offices. This shows the extent of that ancient power, even now reduced as it must be in common with that of the Malay people in general. I had many opportunities of communicating with the natives of Rumbowe, and they have clearly a peculiar dialect, resembling exactly what you mention of substituting the final o for a (...). In fact, the dialect is called by the Malacca people the language of Menangkabowe."
The forgoing remarks apply equally to the three adjoining states, Sungie-ujong, Johole, and Srimenanti, and, as has been aqlready observed, to Naning. It is also worthy of remark, that in the ancient records of the Dutch, preserved in the archives of Malacca, the natives of Rumbowe and Naning are invariably styled "Menangkabowes".
The Malacca Straits and even interior parts of Sumatra and Malay Peninsula for a long time have been an incredible mix of ethnic groups, and this we see mirrored also in Keris.
Regarding Keris Selit, here an old interesting thread, which mentions several restrictive bans as a possible purpose of their emergence. Unfortunately it leaves us without proper facts:
Knowing the character of Malay people, I can imagine them used as actual weapons, at least in 19th cent.