There two things I have accidentally brought through security in the past that didn't get flagged but should have (at least in my opinion).
1.5 liter bottle of water with about 75ml left in my backpack, passed the scanner in LHR
Victorinox Classic SD (it's a small blade but it's still a blade), passed the scanners on multiple occasions when I forgot to put it in the checked bag in HAM, LHR, AMS, SFO, TPE

The amenity kit contents were never an issue (transfer in LHR, DXB, DOH, CDG).