What makes this weapon anywhere near as interesting, useful or powerful as the [Kuva Nukor]?

Rechargeable battery, at the very least. A small innate punchthrough. Got a riven for it, too. More range from the exilus, maybe?

If testing shows the [Tenet Cycron] doesn't proc status quickly enough for Secondary Encumber to be worth using, then Cascadia Flare should be just as good.

It's not going to kill as quickly as the [Kuva Nukor]. But, it's definitely at least reliable enough to replace it and not notice a drastic difference.