One thing you should note though (form your OP) the lychguard have swords, although the printed codex is a little ambiguous (in that they are called swords but referenced as power weapons), the downloadable re-print from GW lists them specifically as power swords - so you might have trouble claiming them as axes.
Nova ruled for them to count as power weapons so thats generally what i base my argument around, though they are classified as power weapons in the armory section of the necron codex so i dont really get why people get hung up on the term "sword" in the weapons name.
But besides that i field a few planes myself and i like how my stuff is kept out of harms way most games until i choose for them to be deployed.
Currently, you are right in that the printed codex only notes them as power weapons, which means you can use the power weapon types from the rule book. However, the electronic Necron codex (which is technically also the most recent) says specifically they are power swords, as opposed to just power weapons. I think you should be prepared for the independent ruling from "Nova" to be superceded by an official correction because it is not really acceptable to have two versions of rules for the same unit from the same army!
In other words, just don't build your army based around the idea they can use axes, because it currently looks like a loophole that is waiting to be filled.
(PS: I have no idea what "Nova" is, and seeing as it's not official GW then it is purely house rule. The only true authority on the rules is GW).
Needless to say, I'm a little surprised that you haven't found scarabs to be very useful. on paper they look great, but importantly they can threaten a range of targets. More to the point, if they come up against those tough to kill multiple wound units such as Nobs, Nid Warriors or even Paladins then it only takes a bit of getting lucky to strip models of their saves completely. I would have thought the threat of that is enough to make them pretty scary?
Have you had any success with scarabs?