Whether you collect vintage or new knives, you need a small "knife maintenance kit".
Here are some items I highly recommend keeping around:
Simichrome polish: for polishing blades, scales, bolsters, and just about everything on your knives!
Break Free (or similar) lubricant
Toothpicks: for cleaning in the tight spaces
Q-tips
A chamois: for wiping down your knives
0000 steel wool: for removing rust and smoothing scales
Neutral shoe polish or car paste wax: for preserving and polishing
A small container of lithium automotive grease: for lubricating the stress areas such as tang/backspring, locking holes, etc.
If your knives have screws or Torx fasteners,
you should include the appropriate drivers.