| Meirril |
It really helps if you provide links to the stuff you want to talk about.
Rod of Splendor
Weapon Tattoo
Pauper's Robes
First, a Rod of Splendor isn't a weapon. The Weapon Tattoo accepts weapons, not just any object. So allowing a Rod to be stored is totally GM's permission territory. Rods can be used as light maces or clubs, that doesn't mean they are weapons.
Second, the Weapon Tattoo removes the weapon from the owner's person. The owner isn't wielding or carrying the tattooed weapon. I wouldn't allow the owner to use Special Abilities from a tattooed weapon anymore than I'd allow them to use the rest of the weapon without unsheathing it. If the Rod of Splendor is allowed to be sheathed in what is an extra dimensional space the the Rod shouldn't be able to boost the tattooed person's charisma. Any magic that removes an item from your person to where you can't find it or use it without magic also means you don't gain benefits from that item.
The pauper's robes attempt to obscure the wearer's identity. If the wearer attempts to use its powers on the Rod of Splendor it should work. The Rod and any clothing made by the rod would appear to be a poor man's clothing...or remain a Noble's costume with a dirty robe over it depend on how the Robe's wearer wants to use its power.