I am wondering if these painted knives are safe to use.
A knife that has a painted blade is best thought oof as a 'gimmicky' knife. There will be limited uses before sharpening starts to flake away the paint on the face of the blade.
The paint itself is pretty chemically non-reactive in most cases (it has to be to harden and stick to the metal).
There are some cases where paints may have harmful compounds. This would have to be evaluated by looking at condition of the knife and the paint adhesion. So, evaluate whether the blade itself is worth using, then keep an eye on it.
In essence, a knife like this is perhaps used under low stress conditions, or as a decorative piece, but any serious cook will not use it for long.