you need DA for upgrades

mysterious stranger

try that

You'll need lottts of money. First travel west of Falconreach to the mysterious guy in the
black cloak. Buy a shadowreaper.
Go do the Crystal clear lake quest several times, and upgrade to shadowreaper of doom
(there is a hidden building in the area accually in the quest). Next go to Artix and do
the haunted castle quest (when you do it, you don't even need to go up the left side of
the castle).
Do this five times and get 5 unlucky doom essences and pay a visit to the cloaked man. If
your a dragon amulet, you can exchange the shadowreaper of doom and the doom essences for
the unlucky shadowreaper of doom.

ok, first u must have 28,000 gold, then go to falconreach home centre, left, left, then u
should see the stranger, then buy it! (click on doom weapon shop)

28,000 gold. talk to the mysterios stranger and buy it.