鞘に収める expression. Meaning?


There are 2 girls who had a fight and are mad at each other.  
One of them asks the protagonist if he is gonna fight against the other girl
and he anwswers:

> 「あいつが邪魔をするなら戦う。  
>  ……まあ、ホントは聖杯なんて物騒なもんはあいつに任せたいんだけどな。  
>  あいつならキチンと **鞘に収められる** し、桜を助けてくれるだろうし」

The the girl:

> 「……そう、でしょうか。  
>  あの人は、魔術師です。  
>  わたしみたいに弱い人間のコトなんて、考えてくれないと思います」

Looking online I found this:

> 元の鞘に納まる:一度別れた男女が、いろいろあった末に結局はもとの仲に戻る（復縁する）ことを言います。

I understand that it means something like get together, but it talks about man
and women.

So, could this expression mean something like:

> Make up, Make peace with each other

Even if it has no sexual meaning?

Alternatively it's talking about obtaining the 聖杯.

Another definition is:

> 鞘に収めた:強い働きかけを止める様子 Stopping a strong influence

I am not sure since 働きかけ seems to have multiple meanings. Looking it up I
found this one:

> 人に対してその物事について考えるよう促すこと  
>  Urging people to think about the circumstances  
>  (Might be wrong how I understood it)

Or does it mean another thing completely?




Two phrases are different in meaning.

> 鞘に収める  
>  …([抜]{ぬ}いた[刀]{かたな}を)鞘に収める

Drawing a real sword means a commencement of battle. The term of this phrase
originates here. This is a thing about spirituality.

> 元の鞘に納まる  
>  …([別]{べつ}の鞘に[入]{はい}っていた刀が)元の鞘に納まる

All sheaths are somewhat different. One sword can be put back in only its
sheath. This is a thing about shape.

Incidentally, the opposite meaning of 「元の鞘に納まる」 is 「[反]{そ}りが[合]{あ}わない」.

反り is the curve of a sword. It shows that a sword can not be put back in the
sheath for the difference of shape. There are many proverbs about sword in
Japanese.




The original expression 元の鞘に納まる is an allusion to a drawn sword going back
into its sheath and is used, in its strict sense, to describe lovers getting
back together after a bitter fight or breakup.

I think the writer may be using the idiom somewhat loosely to mean something
to the effect of: **to put everything back into its right place; to bring a
situation to a harmonious conclusion.**

Or, truer to the image its words evoke, it can be about settling of a fight,
which in this case would be the 聖杯戦争. (Tip of my hat to 変幻出没-san. I didn't
realize this until I saw his/her comment.)

Regarding

> 鞘に収めた:強い働きかけを止める様子 Stopping a strong influence ,

no, there's no such definition for 鞘に収める, I don't think.

(働きかけ is a nominalized form of 働きかける: _to work on someone; to exert
influence/pressure over someone._ )

