What is being personified in the following sentence With that word heat seemed to increase till it became a threatening weight and lagoon attacked them with blind effulgence?

* Heat is described as having a "threatening weight," which is a human characteristic.

* The lagoon is said to "attack" them with "blind effulgence," again giving the lagoon human-like qualities.

Personification is a literary device where inanimate objects or abstract concepts are given human-like qualities. This helps to create vivid imagery and emotional impact.