It's a boss trinket mainly for ranged vocations or melees when they are overleveled for said boss. As MS I'll use it on bosses that get trapped and/or have nothing that would physically attack me/kill me such as Ulu, AB, Tentugly, Sugar Daddy. No one will use it on hunts, it won't be worth it at all, even over 2% elemental trinkets.
Another use case is when you'll charm easy (for you) monsters.
It's indeed extremely niche, should give 2% critical hit chance to make it more reasonable.