Biblical metaphor
Samuel's spontaneous combustion can be a considered an extended metaphor of the play. The act of his combustion is similar to characters in the Bible who have been smited by God and are left as a pile of ash. Loureen is religious, and believes she has truly damned him to hell. While the play resists religious dogma, it does certainly play with the Biblical metaphor.
Saint Loureen
Imagining other women getting word of what she's done, Loureen compares herself to a saint. She sees herself as taking up the mantle of “the patron of battered wives” as the miracle saved her from her own abuse. Without an obvious explanation for Samuel's combustion, Loureen retreats into fantasy and religion for justification.
"Like a ton of bricks been lifted off my shoulders" (13)
Loureen's description of how she feels emphasizes lightness, being unencumbered. Samuel was weighing her down, and now she can feel the relief of that load.
Words as magical
The power of words is the focus of the play, and the two women refer to Loureen's words as though they are some kind of spell, something magic. Florence asks Loureen to come say her words to Edgar, as though they have power in their own right. But of course, it's more of a metaphorical power—the words symbolize power and resistance.
