Sentence:  [H]e takes from the breast pocket of his khaki shirt the little <WSD>seven-level</WSD> screwdriver he took from Michael Amerchrome: Plastic handle insulates, so <WSD>seven-level</WSD> may be used as low-voltage shorting bar, though the metal pen- (pocket-) clip on the handle's side makes you wonder; large enough for a firm grip; light enough to be used as a mallet on delicate components; small diameter of shank permits its use as a probe in confined places or as a chisel to scrape away corrosion between narrow-printed circuit channels; when magnetized, the small shank can retrieve metal parts that fall into restricted spots .... 
Meaning of the word marked with <WSD> tags:  Short for seven-level screwdriver, so-called because it was standard seven-level equipment.