You shouldn't be locking out on pressing movements.Locking out takes all the pressure off the muscles and stright onto the joints and tendons - you have to keep the stress on the muscles at all times to stimulate it even better - it hits the deepest fibres that you wouldn't be otherwise hitting if you were locking out and keeps blood flow into the muscles more efficiently. Start by dropping the weight a little and practice doing the exercises with the proper control, slow on the negative and power on the positive, feeling the muscle work with the heaviest weight you can do in perfect form.
No point in growing big muscles if you don't get tendon development to match it imo
Tendon strength is great if you're into powerlifting but I couldn't care less how strong my tendons are - I'm not into strength training or powerlifting and as long as they are strong enough to lift the weights I use to stimulate muscular development then I'm happy.