A little shoe polish works well for darkening. Also, using tea will do the job. Make a cup of tea and use a Qtip to dab some on for darkening. Furniture companies use it for touch up on leather products. Anything you use, try it on the backside first.
If you use shoe polish, you definitely need a dark brown or black. It will need several coats. This particular holster has taken me awhile to darken since it has a bit of an orange tint to it and I have been darkening it slowly.
You could dust it with a little sand color as weathering and that would further fade the orange.
And I wouldn't have expected Indy's pistol to fit in the holster - the scale issues just don't allow for it to be properly functional (even though I know other holsters have, but to me those didn't work very well visually) unless you oversize it slightly like the old SSC ones.
The open holsters like Luke and Han's can work, but total enclosure like Indy's would be tough because the leather would have to be very thin (like quiver) and would probably be a bit flimsy and also maybe tear. I seem to recall a review saying SSC TOD Indy's pistol won't fit in the holster either.
That came out really good. You are right about the darker areas from the pressure points. Which tea did you use? I also mentioned in a different thread about using the natural oils from your skin to darken leather. You can take your finger and rub your nose or forehead and then rub your finger over the holster or even the whip latch or the shoulder bag strap, etc. It is a slow process as the leather absorbs it. Here is the MFisher holster I darkened that way. Sorry for the poor iPad photo.