"assume you can decide who to kill in close combat, right?" NOPE You roll against the razordons statline, then any secussfull woulnds are randomized between skinks and razordons. (see monsters and handlers rules)
Just clarify, you can't ever attack the handlers in combat, only the monsters. If you wound the monster, a skink dies on a 5+ instead of the monster taking the wound. That said, I also think razordons are very mediocre. It's not that they aren't useful, it's that the things they do the rest of our stuff usually does better. For example, anything I care about enough to want to re-direct will destroy them in combat, so I'd rather throw away 70 points of skink skirmishers doing that than 200+ points worth of monsters. Against large infantry blocks, I'd rather have sallies. Against high toughness, I'd rather have skinks. Against 1+ armor, I'd rather have...almost anything else. Etc. There's some merit to the "jack of all trades" idea, but my experience is that they haven't done enough for me in any one particular direction to make me want to take them again.