LaserHammer is a simple DocBook to mdoc(7) ("UNIX man page syntax") converter.
The command line utility resides in the scripts/ subdirectory; use it like this:
./laserhammer book.parsed.xml book.7
The 7 above stands for section 7 of man pages, "miscellaneous documentation". The 'book.parsed.xml' is a processed XML source of the FreeBSD Handbook; you can use it as test sample. The 'book.7' is the example translated into mdoc.
There's also a rudimentary Python module. Use it like this:
import laserhammer
mdoc = laserhammer.laserhammer(file_path)
print(mdoc)