What is ～やまさりけん and what part of sentence is it used as?


In the scenes of fight in old stories, I sometimes encountered a phrase
～やまさりけん usually in the compound form:

> 力やまさりけん  
>  腕やまさりけん

What is the exact meaning of the phrase and what part of the sentence is it?

> 太郎 **の力やまさりけん** 突き出した槍は相手の体に突っ込んできた。

At first I assumed it was 勝り{まさり}剣, but in the above example it was used in a
spear fighting scene and it does not seem to work grammatically. It seems
neither an adverb nor an adjective.

Also, shouldn't comma be used after まさりけん in the above example?




まさりけん is 連用形 of the verb "勝{まさ}る" + an old verbal auxiliary "けん".

けん means past guess like ～ただろう, so まさりけん is translated as 勝{まさ}っただろう. And
けむ=けん.

I first think や was used as a tone of the word including light emotion in this
case but as choco-san said, や was used as question, so 力やまさりけん is translated
as 力が勝ったのだろうか.

If a comma was used after まさりけん, it might be easy to understand but I think it
is no problem without it.

