1. Physical Strength
One of the most important aspects of weightlifting that can't be neglected. No strength, no power, no tension, no lift.
2. Mental Toughness
You are bound to fail lifts. You are bound to not understand how certain things work or how to make something work. You need to have the resilience to bounce back from all that to get a good lift.
Patience in the lift itself to make sure you don't cut the pull short. Patience in a sense that what you do as training will one day make sense and help you improve.
The barbell is an inanimate object. You need to have the ability to control your actions to make the barbell work for you. You can't use excessive aggression to approach lifting, if not nothing will be achieved.
Intention is what is going to ensure you do well in weightlifting. If you don't have the intention to move fast, you are not going to. Intention is the key to having control over your actions.
Desire is close to intent but in a more general context. Desire is what is going to give you the drive to train hard. Desire is what's going to push you to pursue the feeling of the movement. Desire is what's going to help you improve technique and perform better.
Learning is a never-ending process so being open-minded allows you to see weightlifting from more than one aspect.
Humility encompasses the willingness to accept changes and the appreciation for different perspectives. Keeping this in check will not only allow you to gain more knowledge but also have better interactions with others within and outside of the sport of weightlifting.
Striving to attain these qualities will make you not only a better weightlifter in terms of performance but also a contributor to the development of the sport.