The only half-decent option is the mask from the Fear trial in MPG, but that'd be tough to box!
The only other easily groupable (even soloable) option was the Shissar ring from Ssra during the Fableds a few months back - but it'll be a while until they reappear I'd bet.
Sadly detrimental extension is something you can't get from tribute and the only aug is from LDoN, capped at 65.
It might be worth looking into making Efficiency Awareness 4 potions, they'll give an extra tick up to 74, (or EA5 to 75), and will also stack with any worn focuses you come across.