I have always thought it actually curses the wielder. I also always thought that is immensely cool. Being cursed doesn't do much to someone supposed to stay out of the actual fighting, but you can't really give an artifact like that to a human... Which means you have a strong creature who should not fight. And if he became Feeble Minded...
From the description, I thought that it cursed anyone who was hit with the weapon. Not that I tend to risk its wielders in combat if I can help it - better to have them doing Howls using the Soulstone of the Wolves or whatnot.
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Wormwood and wine, and the bitter taste of ashes.