Romans 15:14
14I myself am also persuaded about you, my brothers, that you yourselves are full of goodness, filled with all knowledge, able also to admonish others.
Paul does not flatten the Romans. He is satisfied that they are full of goodness, filled with knowledge, able to instruct one another. Wesley: full of goodness by being created anew; filled with knowledge by long experience of the things of God; to admonish is to instruct and confirm.
New creation shows in goodness you can practice and knowledge you can share. Mutual instruction is a living church's ordinary work, not an apostle's monopoly. They are able—and therefore responsible—to build one another up.
Calvin hears a concession that disarms pride: Paul writes not because he doubts their kindness or wisdom, but because his office constrains him. Two qualifications fit the one who admonishes—kindness and skill. He ascribes both to them, so they are competent to administer mutual exhortations.
The praise is not in doubt, and it is pastoral strategy. God has already stocked this church with goodness and knowledge. The apostle's later boldness will rest on grace given, not on contempt for what the Spirit has already done among them.