Many of the tools used in the restoration of vintage fountain pens are not at all 'specialist' items. A sharp penknife is always handy for many little tasks, such as removing the remnants of an old ink sac from its nipple before replacing the sac. I now have a very special knife. It was made for me, and I mean every component was hand made, by my brother, a skilled craftsman.
It is very sharp and perfectly suited to the job. It is also a very tactile item and a real pleasure to handle.