The meaning of やわこく in archaic dialog

Question

Reading a novel and there's a part of a sentence that I don't quite understand. For context, the person speaking is at a small party, being completely drunk while speaking to this fit, sober woman.

The speaker is also imitating another person here who tends to speak archaically and very arrogantly. Here is the whole line:

「見通す悪魔が宣言しよう。なんじ、一人シラフで呆れた顔をしている力ごぶ娘よ。アルコールは分解するのにたんぱく質を必要とするもの。今すぐお酒をたくさん飲めば、悩みのカチカチ筋肉が少しはやわこくなるであろう。」

The part that I don't understand is the last sentence,

悩みのカチカチ筋肉が少しはやわこくなるであろう。

There is some talk about 'stiff muscles of trouble' but that's pretty much all I can understand. The やわこく part is especially confusing as I have no idea what that could mean.

Answer 1

やわこい is a dialectal form equivalent to やわらかい. It appears to be used in Sendai (仙台) dialect, but easily comprehensible even to a Standard Japanese speaker.

Thus, やわこく = やわらかく.

悩みのカチカチ筋肉が少しはやわこくなるであろう。
= 悩みのカチカチ筋肉が少しはやわらかくなるであろう。
Thy stiff muscle that botherth thee shall be a bit loosened.

Answer 2

やわこい is a dialectal adjective meaning やわらかい. Many adjectives in dialects of eastern/northern Japan end with -こい. Other famous examples include めんこい ("cute") and ひゃっこい ("cold; chilly"). See this 仙台弁 glossary, too. やわこい is very easy to catch the meaning for standard Japanese speakers, but some are not straightforward.

Note that やわこい itself doesn't mean "very soft".

Answer 3

I think やわこく comes from 柔{やわ}い + こい, so the muscles will become "full of weakness/softness". -こい can also be understood as "having the property of something". 柔い itself isn't normally used, so in this case the word is a dialectal form (Sendai) of 柔らかい as pointed out in other answers.

In the previous sentences, there is talk about alcohol metabolism requiring protein, and drinking a lot of it will weaken the strongly built woman's muscles.

悩みのカチカチ筋肉が少しはやわこくなるであろう。
The stiff muscles that trouble you will become a bit weaker.

It could also be in a positive sense because muscles stiff of trouble is not a good thing. Replace weak with "soft".