I have a home-brewed version that I came up with. It's just an initial draft, mind you, but workable, I think.
4-Inch piece - Ruat: While attuned to the piece, the wielder can cast Cure Wounds. The segment has 5 charges, and each casting costs 1 charge.
5-Inch Piece - Coelum: While attuned to the piece, the wielder can cast Slow (DC 18). This cannot be used again until the next dawn.
6-Inch Piece - Fiat: While attuned to the piece, the wielder can cast Haste. This spell cannot be used again until the following dawn.
8-Inch Piece - Justitia: While attuned to the piece, the wielder can cast Gust of Wind. This segment has 5 charges, and each casting costs 1 charge (stacks with Ruat).
10-Inch Piece - Ecce: While attuned to the piece, the wielder can cast True Sight. You cannot use this spell again until the following dawn.
12-Inch Piece - Lex: While attuned to the piece, the wielder can cast Hold Monster (DC 18). You cannot use this spell again until the following dawn.
15-Inch Piece - Rex: While attuned to the piece, the wielder can cast Heal. This spell cannot be used again until the following dawn.
1 Segment: The person attuned to the rod becomes very orderly and fastidious. Improve Charisma by 1 point (to a maximum of 24). If faced with something that is disorderly, the character must succeed on a DC 15 Wisdom saving throw or become distracted, causing disadvantage on Attack Rolls, Ability Checks and Saving Throws until he leaves the area or spends a reasonable amount of time putting it in order.
2 Segments: While attuned to the artifact, you can cast the Fly spell at will. The wielder will no longer accept random circumstance to determine actions, requiring some other sort of logical conclusion. The wielder's alignment shifts to Lawful, though his good, neutral or evil portion remains unchanged.
3 Segments: While attuned to the artifact, the wielder gains advantage on all saving throws to resist spells or magical effects (other than those from the Rod). The wielder refuses to break any law, no minor how minor the infraction, unless he can determine some sort of legal loophole.
4 Segments: While attuned to the piece, the wielder can cast Control Winds. Roll 1d6. On a roll of 1-5, you cannot cast it again until the next dawn. The rod also can be wielded as a +1 Mace. The wielder cannot deliberately tell a lie. The wielder's alignment shifts to Lawful Neutral. The wielder refuses to give up the artifact at this point, remaining attuned to it.
5 Segments: While attuned to the artifact, the wielder can cast Control Weather. Roll 1d6. On a roll of 1-5, you cannot cast it again until the next dawn. When subjected to strong emotions (anger, hatred, or fear), the wielder must make a DC 15 Wisdom saving throw or be unable to act for 1d4 rounds. He will be unable to attack or cast spells, but he can still defend himself.
6 Segments: The wielder must take everything literally. If charmed or commanded, the wielder will follow the instructions to the letter. They lose the ability to distinguish sarcasm.
7 Segments: While attuned to the piece, the wielder can cast Greater Restoration. Roll 1d6. On a roll of 1-5, you cannot cast it again until the next dawn. The rod also can be wielded as a +3 Spear. You are now rigidly Lawful Neutral. Anyone who does something that is against your code is perceived as an enemy.
