Must touch with suction cup for full sensitivity

Must touch with suction cup for full sensitivity is listed as a Nuisance Effect for the Detect ability of the Decabrach in GURPS Template Toolkit 2: Races
This is the same value as Half Damage Without Grapple from The Weird and probably functions like that, because it's taken in addition to the normal Melee Attack limitation.
Just instead of halving damage, it probably reduces in some other way.
Category:Nuisance Effects