A good starter weapon for off-mystic guardian investigators. It doesn't take a slot for Lilly Chen and its the ability to get a +2 on tap for a +1 dmg is great for Sister Mary, who struggles to push her fist to reasonable amount. Note that it doesn't have a supply or amno cost attached for a relatively cheap weapon (3r for one handed). The doom can be mitigated if you have another weapon (enchanted blade) or spell besides it in case of autofail on the first attempt to kill a 3hp enemy.

It can be a great pick for Diana as well, since it starts at a reasonable amount for skill tests (3+2) and can be further boosted with daring. In mid game, you will probably be capped in willpower and have some other boosts to complement it. Since it's an item and a weapon, it can also be tutored with back-pack and prepared for the worst, which can be another argument to go for it as those tutors also fetch for her mandatory signature.