Nobody thinks it'd be unwieldy? Really?
After all those pre-TFA videos where lots of people demonstrated how a crossguard could hurt the user?
Actually, I saw a really good video where the guy (who was quite proficient with a broadsword) had dipped the cross guard into white paint, so that anytime the cross guard touched his arms, it'd be very obvious.
After several minutes... there wasn't a spec of white on his arms or wrists.
So an energy crossguard is only a problem if the wielder is an incompetent swordsman. Something that Kylo Ren certain was not.
I don't know about that, because he took his time defeating Finn who had never used a lightsaber before, and then lost to Rey who also had no prior training.... But I digress :-)