In the original game, all items will respond to the dummied-out magic meter upgrade except for the Lantern and the Magic Cape, which will remain unchanged from the 1/2 upgrade. If you are using a patch that enables the 1/4 magic meter, you will need to edit 2 bytes to bring these items up-to-speed.

Lantern
x3B299 02 > 01
(drops magic consumption from 2 to 1)

Magic Cape
x3ADC1 08 > 10
(increase frame count between magic consumption from 8 frames to 16)