I will add something from myself, because I have already sharpened several thousand pliers, so I have some experience. There are plenty of sharpening methods, but the main thing is to:
1.the most important - do it carefully, because what is grinded will not come back, and sometimes it is difficult to remove the blade if it is grinded too much
2. tools / devices recommended by me - a water stone (the easiest and safest) with a slow-speed water grinder with a stone of min. 300 or e.g. 1000, or with a needle file (here you need to know what's going on and have a steady hand, a decent file and experience, because 3-4 moves and it can be on the edge)
3.How to sharpen? - First of all, check if the blade has no burrs, no bent tip, whether it converges evenly - when crimping, the tips of the blades should be on the same plane.
At the beginning, just tighten the pliers and gently align the plane from the front of the blade. Besides, the rule of thumb is that you only sharpen the inside of the blade and it is important to maintain the cutting planes. Ie. inside the blade there is a plane like here in the youtube video searching for "mai kem"
4. It is also worth checking if the pliers have no play - then all you need is a hammer and a punch and one or two hits on the rivet - joining the pliers arms. The rivet is there even if you can't see it because it is ground. You should just be careful not to destroy the blade with an inaccurate hit.
5. It may happen that you will not be able to properly sharpen the first cutters. Take this into account and if they are expensive and professional cutters, it can be a problem. That is why it is worth trying on some old and cheap version of the clippers to "get" what it is all about.
Good luck!
