You mean like using a guardian spirit talisman or moment talisman? I haven't tried out most of them, but Paired Raiken and Kato have really easy-to-aim ones that pretty much guarantee an instant elemental status on an enemy.
I hate the summons that are hard to aim. Like Kara-jishi, he comes out a set distance in front of you, so if an enemy is running at you, he ends up appearing BEHIND the enemy and missing completely.
If you mean Living Weapon, I don't know. Basically anything with A or A+ Tenacity is godlike, if you actually wait until you're at less than 30% health to summon.
I've said this before, but using Kato or Paired Raiken (A and A+ tenacity respectively), if I wait for critical health, without ANY OTHER SETUP OR CONSUMABLES, I can maintain living weapon for full missions.