I agree with Andy. When doing this type of finish by hand, using a brush, it's best to allow for this at the start, and use thinner paint, or a 'damp brush' technique, for the 'squiggles' etc. However, as it's now done, I wouldn't do any form of sanding; there's far too much risk of ruining what appears to be a good result.
Personally, I'd give it a coat of gloss enamel varnish, if possible, followed by one or more thinned coats, or acrylic gloss clear, then the semi-matt finish coat to simulate the Luftwaffe paint finish. By using enamel clear gloss varnish neat, it should even out the appearance without detracting from the colour tones or effect, and giving a 'thick' enough basis for the following thinner coats to give it an overall smooth, even appearance. Until I got an airbrush capable of doing mottle etc in smaller scales, this is the way I used to tackle all Luftwaffe mottle/wave schemes, with acceptable results.