In other news, I'm surprised you characterize that as nice grain. Looks like branch wood to me, and would be an automatic blast anyway. Maybe the photo misleads?
Ok the grain isn't $1000+ super high grade quality but it's clean, the orientation follows the shape and other side has nice flaming and the front and back are solid birdseye. It's nice to me, probably not good enough for some of you guys but it's probably a lot better than most English pipes have ever been made of lol
Forget the blotchy spots. On the driver side, there is at least two big areas of bald spots. Bald spots look to be really fine grain and they are usually very clean. Blast it 100%. You can usually spot bald spots before you cut into the briar, and it is best to cut them out then draw the shape if drilling first. If shaping first, work around them or cut them off.
I have a kit pipe a friend made that seems to have lighter blotchy spots on it. I think he got the kit from PIMO. I'm not sure this helps, but I hope it does.
On land, at sea, at home, abroad,
I smoke my pipe and worship God.
I've seen similar things on some apple blocks I boiled. What happened was MOLD. It will stain the wood. I saw some small blue/black mold spots starting to develop (I didn't seal it well enough with wax) so I decided to sand off those areas and reseal it. I had to sand pretty deep; the mold spots seemed to stain underneath them pretty deep. It looked very similar to what you have there. I think it's just stain from mold, not necessarily moldy wood.
What could also help would be soldering over those spots with oxygen and silver.