What does causative + もらう + volitonal mean? 使わせてもらおう


(Upon receiving a sword as a gift)

ありがたく使わせてもらおう

I know させてもらう means "I'll take the liberty of doing x" but does the same a for
使わせてもらおう?




More or less in my opinion

As you know, させてもらう is the causative て form of する and the verb もらう. Together
as させてもらう it roughly means "I'll will do X (because I have permission / I was
allowed to)" in a more literal sense

Some things to remember are that the causative form can imply someone was
forced to do something or was allowed / given permission to do the something
depending on the context. And that て form verb + もらう can mean "to get someone
to do verb​"

In this case of someone gifting a sword and another person responding with
ありがたく使わせてもらおう, it's really no different in the end

Instead of using causative て form of する (させて), they are just using causative て
form of 使う (to use). So this can be seen as "I'm grateful for being allowed to
use this (the sword) and so I will (get myself to) use it"

