Some beardies are skittish about having their tail handled and some don't seem to care. If they don't react, it doesn't necessarily mean that they have no feeling in their tail.
The end of our beardie's tail tends to be a little darker than the rest of him sometimes too, depending on where he's at with his colors (cold, warm, stressed, happy, sleepy, etc -- there's a different color for each), probably mainly because he sheds in patches, and parts of his tail have usually shed more recently than other parts, so they tend to be a slightly different color. My husband asked our vet why the end of his tail was darker, and she told us it was due to retained shed. The only time you would need to be concerned about that is if the shed doesn't come off all the way around the tail (or a toe, as well) and cuts of the circulation, but as long as you keep the shedding skin moist so it doesn't get hard and tight, you shouldn't have a problem.
I agree that your beardie's tail looks fine in the photos
(and doesn't look like there's any shedding going on at the moment either).