Nice post Gilles! So that's where that set went....
Steve, your posted set is most likely commercial. Here's what I've been able to piece together, as well as a few of my examples.
There are actually two types of purple DPM attributed to Swaziland. There is the purple/bright blue pattern of the Royal Guard (Gilles set), and then a purple/dark blue type purportedly used by the Swaziland police. I've never seen a photo of either pattern in use, so it's hard to say. The only photos I've seen of Swaziland police show them wearing all blue uniforms. Here's examples of the "police" issue purple/dark blue DPM:


As you can see, the bush jacket is cut just like SAP bush jackets, and just like Gilles' Royal Guard bush jacket. In regards to the pattern, note the Royal Guard pattern has a light blue base color, whereas this "police" pattern has a light gray color. The blue in the Royal Guard pattern is brighter as well. Also note that the police pattern has quite a bit of the dots associated with the black shapes in the pattern. The Royal Guard pattern has them to some extent, but the patterns are not the same.
Now, to muddy the waters even further, there is another police variant, which is what Steve has posted. This pattern has a dark ash base color instead of the light gray, and the pattern has a much darker look to it. I suspect most of these are commercial, as Camo Joe has offered this pattern for at least the last ten years. Check it out:
http://www.camojoe.co.za/
Go to "clothing" and then check out the "night camo". The question then becomes, has the Swaziland police procured any of the Camo Joe uniforms for their use? I have no idea. But, I would suspect that most of this pattern in collector hands is in fact commercial. Not that I'm totally convinced of my above posted sets either, but they are clearly different. Something else that doesn't sit well with me is that none of these "police" items are properly marked. They all just have size tags. Swaziland Defense Force items are usually very well marked, and note the tag in Gilles' Royal Guard set. I know lots of folks assume that African countries don't properly label their uniforms, but that's generally not the case.
Anyway, here's a couple of the Camo Joe pattern items, to include a shirt that came with my items posted above. Another wrench in the works is the sergeants rank brassards, which seem quite genuine to me.



Well, that's all I have on the Swaziland purple DPM patterns. As you can see, absolutely nothing definitive.
Cheers,
Mike