I need more caffeine before I think. This is the type of thinking hard that I am trying to recall things and it is thus very hard.

There are many weapons in the various "celtic" derived cultures (so I am referring to things like Irish, Welish, Scots, etc) tied to a spear of Lugh (which would be the Irish name for this character) but also similar weapons that always hit their mark whether thrown or stabbed.

https://en.wikipedia.org/wiki/List_of_mythological_objects#Pole_weapons

But of the many weapons of lugh (which may be the same weapon or different weapons) they had lots of properties that made them famous, never missing the mark, associated with fire and burning, smiting, slaughter. So yeah look into these myths and find a word either about the weapons or what the weapons do that you like.

Also if I recall Lugh threw a stone at his grandfather the God / Demon Balor who had an eye in the middle of his forehead that could kill anything the eye saw. (Though in some myths it was a spear not a sling stone.)

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Looking at the wikipedia link while writting this and I am seeing Gae Assail (Spear of Assal) which has the command "Ibar (Yew)" to always hit the target and "Athibar (Re-Yew)" to return to the hand of the person who throws it. This would be a celtic culture and thus celtic language tradition.

This reminds me of the similar Germaniac tradition where there is the Eiwaz or Eihaz rune / letter which represents the concept of the Yew tree. Now in later germaniac myths such as the norse version Yggdrasil is an Ash Tree, but in earlier myths it has been speculated / hypothesized it may have been a Yew tree for various reasons.

I am not sure how much I believe this (and how much of this may be 1800s, 1900s, and 2000s New Age stuff where people try to recreate ancient cultures and feel connected) but the Yew Tree is often connected with with Death, Rebirth, and Transformation. Perhaps word related to Yew or Eiwaz or Eihaz.