I'm currently level 44 and have just recruited Kharjo. However, he keeps getting owned by enemies and close to death on many occasions.

I read that followers now level with you - and that Kharjo goes up to level 81 - but, if it wasn't for all the restore health potions I give him, he'd have died many times over by now.

I haven't levelled up since I recruited him, so I wonder if that might be the issue. Or, could it be the rubbish blades armour that he now wears instead of other, better armour? Even when I give him upgraded blades armour, he refuses to wear it....

Also I tried the Wabberjack 'fix' on him but that made no difference.

Does anyone have any more colour on how the follower levelling works and, specifically, for Kharjo?

Most followers have level caps, see this for yours

http://www.uesp.net/wiki/Skyrim:Followers

Kharjo doesn't level to 81, that's the Khajiit Mage, J'zargo.

Ah ok, thanks guys. Pretty disappointing that kharjo caps at 30 when I thought they now levelled with the player. Oh well.

If you're on PC, there is a console command to set their level to match yours.