This is one of the - sadly - MANY errors and failings in The Book of Skelos.
In the core rules there is the Subtle X Quality. But there is no “Unsubtle X” Quality described.
But in Infinity there is the Unsubtle Quality:
Unsubtle X: This item is unusually overt, drawing undue attention each time the item is used. Any Observation tests made to detect the use of the item are made at −X difficulty (minimum 0). In addition, silent actions using the item are increased to sneaky actions; and sneaky actions are increased to noisy actions.