After many years, the best tool I have found to edit/slice/cut/tweak/join/modify videos is.. Movavi. I often use it to cut out the bits I don't like, or to slow down different parts, or to join different files together.
Extremely powerful but lightweight, it supports these functions:
- Visually cut/slice any number of clips from any imported videos, with high precision, either on timeline or in a special window
- Join/re-organize sliced clips any way you like on a new track
- Slow down / speed up
- Apply FX such as brightness/lighting if too dark
- Save the new edited video in exactly the same format with no degradation in quality
- All formats supported
Worth of every penny of its price tag of just 28 USD.