Yes, False Water Cobras are rear-fanged venomous. Their venom is not potent in comparison to front-fanged venomous snakes such as Vipers or Elapids, though. Caution should still be taken with handling, but their delivery apparatus is poor given the fact they have to essentially “chew” on you to really envenomate. I’ve been envenomated in the past as a result of complacency, and while it certainly wasn’t pleasant, I only experienced a little pain, redness and swelling for a few days. Picture below for reference, taken 20 minutes after envenomation.
They can be a little nuts as juveniles; their younger years are when you have to be the most cautious because their smaller size makes them incredibly fast and they can be very eager to eat so they will chomp down on anything at first. As they mature into adulthood though, their personalities begin to shine and they really transform (most of them, anyway; they can still remain rambunctious, there is no guarantee).