I am not now nor ever under the impression they are military hardware. It merely seemed that him having Raising Heart made no sense except in the form of being convenient to the plot so he could give it to Nanoha. His own Magic would not seem to be on the same scale as her's, and as such, why would he have a device that powerful.
When Nanoha first gets Raging Heart, some things are mentioned that are, as far as I am aware, never brought up again. One is that Raging Heart was Yuuno's personal intelligent device that he transferred control of to Nanoha. I've gotten the impression from the show that Raging Heart is only so powerful because Nanoha herself is so powerful. Yuuno couldn't use it at the start of the series because his injuries left him too weak to even assume human form for quite a while, though he evidently recovers mostly by the episode where he creates a zone so Nanoha can battle the giant cat without drawing attention. This doesn't explain why Yuuno never gets another device; maybe his skill had progressed enough from when he first got it that it was little more than a calculator for him, a crutch that he no longer needed, and he just lacked the raw power to access the higher level functions that make them necessary for combat mages. We know nothing that I am aware of about how Yuuno got it in the first place. Maybe he had family connections that got it for him, maybe he was testing out the new design, maybe, maybe, maybe...
Probably has something to do with RH's sealing form. He wasn't intending to use it for giant fuck-off beam spells, he just needed a way to hang on to the Jewel Seeds without setting them off. It's possible that you need a device of RH's power to hold those kinds of Lost Logia.
This was posted while I was typing, but I like this reason for why he needs a device advanced enough that he can't use all of its functions.