Right, here's what I think we should do, Kalin. Note that I'm not changing everything, just fleshing some things out. I'm hosing the Ring and Key, changing the Scales, making the Necklace a real Fateseal (almost, KCVDS has a restriction on that), and cranking up the power levels of the Eye and Puzzle (A slightly better Ceremonial Bell and Card Trader, really?). Hooray!
Note, none of these abilities are treated as the effects of cards, and the Items are not treated as cards. As such, Solemn Judgment and similar cards cannot be activated in response to these abilities.
Rod: Once per turn, and twice per Duel, the holder may take control of 1 monster the opponent controls. This ability can only be activated when a Spell Speed 1 card can be activated and does not start a chain.
Ring: Once per turn, the holder may send 1 card from their Deck to the Graveyard, OR remove from play 1 card in their Deck. This ability can only be activated when a Spell Speed 1 card can be activated and does not start a chain.
Scales: Once per Duel, the holder may pay half their life points to destroy all monsters, OR all face-up Spell and Trap Cards, OR all face-down Spell and Trap cards the opponent controls. This ability can only be activated when a Spell Speed 1 card can be activated and does start a chain.
Key: Three times per Duel, the holder may change the battle position of 1 face-up monster. That monster's battle position cannot be changed. This ability can only be activated when a Spell Speed 2 card can be activated and does not start a chain.
Necklace: Once per turn, the holder may reveal the top card of either player's Deck and put it back on either the top or bottom of the Deck. This ability can only be activated when a Spell Speed 1 card can be activated and does not start a chain.
Eye: Once per turn, the holder may look at all face-down cards on the opponent's field, OR all cards in their hand. This ability can only be activated when a Spell Speed 1 card can be activated and does not start a chain.
Puzzle: Twice per turn, the holder may return 1 card from their hand to their Deck to draw 1 card. This ability can only be activated when a Spell Speed 1 card can be activated and does not start a chain.
Hope you can put my ideas to good use. I think we should discuss the rewards for beating the holder of each item sometime soon, but until then, play around with this stuff as much as you like.