What does すら mean in this sentence?

Question

気持ちは分かるがお主はもう既に このわしすらしのぐほどの力を身に付けてしまっておるからのう｡

この場合の「すら」は「より」と同じ意味ですか？

Answer 1

すら has the same meaning as さえ, but sounds more old fashioned/stiff. It can replace を, which is what it looks like it's doing in this sentence. For example:

これを読めば分かる。
If you read this, you would know.

これさえ読めば分かる。
If you just read this, you would know.

さえ shows a minimum example. In your example, it would be similar to the english "even".

気持ちは分かるがお主はもう既に このわしすらしのぐほどの力を身に付けてしまっておるからのう｡
I understand how you feel, but you have surpassed even me in power.

より would not make sense in this context. しのぐ is a verb and cannot come after より. Like the examples above, すら is replacing を, which would have marked the object of しのぐ.

Related Post: Does さえ mean “even” in the following sentence?