Martial Arts Skills in Chinese / Japanese...

武技 can be translated as “martial arts skills,” “warrior skills,” or “military skills,” depending on usage.

In both Japanese and Chinese, rather than meaning martial arts, this speaks more to the skills that you possess in regard to martial arts. This phrase also has a light suggestion of “having the itch to show off these skills.”

練功 is a martial arts term that can mean to practice and attain working skills, feats of practice/practise, or skills acquired through hard training.

練功 is often used as a martial arts term but can apply to other skills (or professions).

不怕练不成就怕心不恒 literally translates as: Do not worry about not being able to master [a skill]; What [one should] be concerned about is lack of perseverance.

Figuratively, this means: One's skills cannot be perfected without perseverance in practice.

For me, I've learned that you can only get so much from school or studying. You've really got to do “on-the-job training” to perfect your ability and skill.

For martial arts students: You can read about a kick in a book, or someone can tell you about a certain kick but until you practice the kick, there's no way you'll master it.