translate soul releaser into Japanese

I’m naming a sword and my students came up with ‘soul releaser’ as in after it kills you. We researched and came up with ‘ Tamashii o kaihoo’ 魂 解放 but want to make sure it’s correct grammatically.

"tamashii o kaihoo" is grammatically correct, but it means "release soul" instead of "soul releaser".

"魂 解放" is grammatically correct, but it's not read "tamashii o kaihoo" and it means "soul release" instead of "soul releaser". Also, I don't really think it correctly interprets what you're trying to say, but then, I'm not really sure if I understand what you're really trying to say. I hope you're not trying to kill anyone including yourself.

Agreed.

Soul = 魂
Release (in the sense you are looking for) = 解放

Those individual words (both are nouns) are correct. But to give that sense of “soul release-r,” it would have to be a phrase, sort of a pretty mundane-sounding phrase (or a sentence) that I doubt it would be good for a name?

Releasing the soul/release of soul (noun phrase) 魂の解放
The one who releases the soul/release-r of soul 魂の解放者
(It) releases the soul　魂を解放する　For short, you “could” go for 魂を解放

How about 鎮魂刀（ちんこんとう chin-kon-too）or 鎮魂剣（ちんこんけん　chin-kon-ken (刀 too and 剣 ken, or turugi, all three mean a sword.
Or, 鎮魂乃剣 chin-kon-no-turugi, tama-shizume-no-turugi)?

Different from the Christian notion of releasing a soul from its body, 鎮魂 means to wish a soul its peaceful rest, like in the case of a catholic prayer of Requiem (aeternam dona eis, Domine). Requiem, as the name of classical music piece, is translated in Japanese （鎮魂ミサ曲）.