How to darken / heal bright spots while retaining texture

[Blighty]

Create a duplicate layer on work on that. If you don't like your edits just delete the layer and start again.

Select a suitable ForeGround colour (eg 20,20,40). (Experiment with different values to get the effect you want.)

Select a brush and set the brush Mode to Darken Only. Paint over the bright spots.
(Alternative: create a transparent layer above and set the layer mode to Darken Only)

(Use Undo and try again.)