When S. Africa was a Dutch colony, there were quite a lot of Malay slaves brought from Indonesia ( ever tried South African national dish call Bobotjie?). But they were mostly from Java and a bit from Sumatra.
Oom Kruger lived much later, when the British were in control and the importation of foreign workers was limited to the Indians ( Gandhi started there). Also, he never, ever left S. Africa.
If it indeed came from S. Africa, it was likely a souvenir, or ... I bet there was a ton of crazy Brits and Boers who collected sharp and pointy things
