I *STRONGLY* recommend against giving cohorts PC 'levels' of equipment.
A cohort is supposed to be weaker and less important than PCs. He is a minor character in the 'novel' of your game. He isn't supposed to make a difference.
A cohort fighter is supposed to stand by his PC wizard and guard him against attack. He is not supposed to be strong enough to stand on the front lines in every battle.
Sancho Panza was a type of cohort for Don Quixote. Aram is a cohort for Perrin (Wheel of Time).
There are no cohorts in the Star Wars movies: each character is important and plays an important role. There are no cohorts in the Lord of the Rings: each member of the Fellowship plays an important part at one time or another. Hutch was not Starsky's cohort. The Bear was not BJ's cohort. The Fat Man was not Jake's cohort. Vir wasn't even Londo's cohort (Babylon 5) because he was too central of a character.
Cohorts support. They do not lead or stand as equals. The feat is 'leadership', not 'second character'. The PC may actually need to help protect the cohort at times to keep it alive.
Giving the cohort PC levels of gear puts him close to even footing with other PCs. Instead of being a small character in the game, it becomes just another PC. 2 levels of experience is a difference in ability, but not nearly enough if the cohort has PC type equipment.
I've seen many cohorts done many ways. The ones that worked best were background characters that were hard to define without referencing the PC. The ones that worked worst were the heavily armed cohorts that were built to min-max the abilities of the PC instead of being built as fully fleshed out NPCs that happenned to follow the PC.