True heavy duty exercises will require tendon/ligament/joint involvement, of course. But there are way's to make 10lbs feel like a lot more. Actually bi-passing the extreme tension felt on those tendons/ligaments/joints. And having the muscle it's self handle the bulk of the work.
A few come to mind. The old One and One Half system. Excellent for muscle size and more joint friendly due to the much lighter weight used. As are 21's, another effective scheme that does not require a lot of weight. As for an exercise, the Bent arm pullovers (BB/DB) is very good. As are Push Backs/Push Off's. Great advantage here because the shifting of bwt, as you are doing this exercise, can make the resistance feel like 10 to 100+lbs. KickBacks, as offered by Mass04, are good. Though I might suggest using DB's because of the grip advantage obtained.
A proper hand grip can be important, but just as important is the elbow placement in most any exercise. Elbow position can added unwanted stress, or reduce it greatly, on the movement of a joint.
If still having problems with the elbows, even with the lightest weight, than take 2 or 3 weeks away from the cause of the problem. To my way of thinking, direct extension exercises (overhead/lying) are not needed and may cause more trouble than they are worth for most men. Personal view...that's all...compound movements can be most effective for tricep mass in the long run. Exception might be tricep pushdowns or tricep pressdowns. Good Luck.