In seriousness, Silas, I think it's a mistake to assign the Knights to any specific niche.
Let's make a few assumptions.
(1) Cyberknights have no automatic advantages that no one else can possess.
(2) Cybernetic "kits" are easily customized, and may be designed for certain areas of focus at their core, but adapted for all manner of different roles through modular reconfiguration. This is in keeping with DUST's intended Eve-like fitting scheme.
(3) Quality of such kits, and modular add-ons, may vary.
(4) Cyberknights, as an order, have access to
very high-end tech and training.
(5) The Kingdom has access to all the run-of-the-mill ground-pounders it needs. Cyberknights are emphatically not regular forces.
If we take the above as given, the likely role and the purpose of the Cyberknights becomes a bit more clear: probably, they are irregulars in the most interesting sense. Each knight trains heavily in some specific, and possibly unique, role, becoming a specialist in a particular area. They stand out from regular military or security forces both by the training and technical resources available to any given knight and by the freedom they have to set their own tactics and equipment.
An order of well-funded elite agents, sworn to a specific cause (defense of the Kingdom, perhaps from a specific group or specific type of threat, perhaps just in general, being the norm here), and whose loyalty is considered beyond question without solid evidence to the contrary, possessing capabilities and tactics that vary enormously from individual to individual, would be a titanic headache for any hostile organization to try to prepare for and defend against.
Of course, they're probably nearly as much of a headache to try to work with or around; probably the detectives and such of the Khanid Kingdom's finest are known to complain bitterly about certain bits of knightly mischief: "I'd been working on rounding up this ring of bastards for three years-- three years! Then this armored psychopath gets a bee up his backside, breaks up the crucial meeting before we can make the bust, shoots half the participants, and delivers my informant to my boss, trussed up on a plate like some kind of damned trophy!"
Having your loyalty be beyond question doesn't mean that all's fine and dandy with the rank and file, after all, and "knightly order" can start looking a lot like "well-equipped band of vigilantes" if they don't watch their step REAL carefully.
Edit:
Oh-- and the above might provide at least one reason for cyberknights to actually carry swords: initial identification of an otherwise-diverse organization at a glance. Of course, if that's so, carrying a sword in the Kingdom if you're NOT a cyberknight could very well be a serious crime, itself. Call it "impersonating a paladin."