Do not mention the terms "techniques" or devices at all in your essay, it shows that you are merely searching for devices, and not the task which is to analyse the piece as a whole. I was taught that LA was all about identifying techniques and just P.I.S.Sing in year 11...needless to say it messed me up bad for the LA at the start of the year, C+ lol....
Focus on the essay as a whole, "zoom in" on certain terms or words and analyse the language. Personally I at the moment, try and have 2-3 paragraphs on wide angle observations, and 1-2 paragraphs analysing specific use of words/phrases, just depends on the way in which it is written.
Yes you can say something like "the author attempts to use his authoritative position to sway readers...", which is pretty much a technique, but avoid summarising these things in the intro/conclusion by saying "through use of ..... techniques/devices",