What are you the deity of?
I am the deity of oaths, agreements, pacts, and contracts.
What powers do you gain to perform your duties?
Oath Deity; As a deity of Oaths, I possess a myriad of abilities related to the governance and maintenance of my dominion. Such as:
Divinity
Oath Embodiment; As the principal being of oaths and their variations, the user embodies it's various qualities, and acts as a nexus that binds oaths and their users.
Oath Manipulation; The user has nigh-absolute power over the dominion of oaths. They have immense authority over all oaths made, by divines, mortals, monsters, and spirits alike, and have the subsequent ability to enforce these agreements. They can forcefully preserve the agreement made between the people within the agreement, or in very rare instances, even void the oath entirely. In order to further uphold the legitimacy of their domain, the user can hand out due punishment and rewards based upon the premise of the oath. The user tends to also act as an intermediary to verify and clarify all things made within an agreement, as they have all the context for the agreement, and can set the conditions in place.
Nigh-Omniscience; Regarding anything related to oaths, contracts, agreements, and pacts, the user will have near infallible awareness.
Honorable Divine; As a divine charged with the maintenance and holding of people to their word, they are considered amongst the most honorable of deities, especially considering they never break their word.
Guardianship; User guards over and maintains the legitimacy of oaths, and acts to maintain or avenge them.
Punishment Manipulation; As the upholder of oaths, the user has the ability to enact due punishment on those that intentionally go against their agreements.
How do you contribute to the construction and/or maintenance of the universe?
I won't have much to do with the construction of the universe, but it's subsequent maintenance.
Words are cheap, this is a known truth. As binding as an agreement or contract may seem, it is inevitably just a vassal argument. However, in this world, there will be a way to make the contract truly binding. By contacting the god of oaths, mortals, gods, and anything in-between or beyond, can have divine law placed upon their agreement. Therefore, depending on the clause, the individual who breaks the agreement will be unable to escape punishment, or will be unable to break it, even if they try.
In this way, people cannot so easily go against their words, lest they face divine judgment. Even gods, in their hubris, will have to stay honest once a proper agreement has been formed. This will help maintain the order of the world, and prevent the gods from being too out of sorts.