If you had just included a few verses further on, that would have linked in how God's righteousness 'works'. It explains how Gentiles sought the righteousness of faith. Sadly, the Jewish nation that had God's righteous law sought to obtain God's righteousness through law-keeping and failed. Why? Because God's law is so utterly sinless (perfect), no human can keep it (apart from the sinless Son of God, Jesus Christ.)
God's righteous law exposes all of us as unrighteous sinners. As Romans chapter 10 goes on to say, we have to submit ourselves to the righteousness of God, "For Christ is the end of the law for righteousness to every one that believes...For with the heart man believes unto righteousness; and with the mouth confession is made unto salvation."
When we see how the righteousness of God was publicly displayed on the cross of Christ, then we understand Romans 9:21. The power of God unto salvation was demonstrated to the world, but the world couldn't see it (and still can't). Because the sinless Christ agreed to become sin and bear the punishment for all sin, then God could freely pardon those putting faith in Christ without violating His own law. His law states that all sin must be punished. Christ took that punishment. Now all who confess their sin to God and put faith in that means of having sins pardoned become vessels of honor. Previously, they were vessels fit for destruction as the wrath of God was due to them, for their sin. But faith that accepts the righteousness of God delivers from such wrath.