Whilst what you say IS accurate... He was powerful enough to stop blaster fire in midair at the same time as paralysing Poe at same time. Feats we haven't seen from the most powerful Jedi Masters or Sith Lords!
They may be the only tricks he's "mastered" as he is weak in other areas and this is good enough as so far he has been un-opposed. When he comes up against others strong in the force these tricks will be useless.