It should be fine. It may seem like a lot, but if you have a well rounded 4 person group they should be okay. While investigating, we knew what we were looking for and swung by the library and discovered they are vulnerable when they are disarmed. Further, in our campaign, they ran when their numbers got low (this might have been our DM realizing we were indeed taking a bit of a pounding and changing the encounter though). Try to hint to them that Vendelfek could be useful.