Trap One: Too Much of a Good Thing
The moment you can name devices, the temptation is to cram in as many as possible. Resist it. Devices are spice, not the meal. Put everything in threes, repeat every phrase, end every sentence with a rhetorical question, and the listener stops hearing the message and starts noticing the technique. When everything is emphasised, nothing is — the punch numbs into noise.
Trap Two: a Device Is Not an Appeal
This one trips up even good students. A device is the tool; an appeal is the job the tool is doing. A rhetorical question is a device — but whether it's pulling logos (making you reason) or pathos (making you feel) depends on the question. “Can we really afford to wait?” leans pathos; “If three streets flood now, what happens with twice the rain?” leans logos. Same device, different appeal. Remember the link back to ethos, pathos and logos: devices carry appeals.
Trap Three: Naming Isn't Analysing
Spotting “that's anaphora” is step one, not the answer. The marks live in saying what the device does to the listener: anaphora builds an unstoppable drumbeat; a tricolon gives a sense of completeness; antithesis sharpens a choice by clashing two opposites. Name the tool, then name the effect.