Professional knife sharpeners restore blade edges using diamond, ceramic, or whetstone abrasives. Electric models offer consistent 15-20 degree angles with two-stage sharpening. Manual systems include pull-through designs and guided rod arrangements. Japanese whetstones (1000-8000 grit) provide finest edges for precision work. Diamond plates cut faster than ceramic alternatives. Honing steels realign edges between sharpenings without removing steel. Quality sharpeners cost £40-200. Professional services charge £5-15 per blade. Regular maintenance extends knife life by 3-5 years.