The spelling of "sware at" may seem unusual, but it reflects the pronunciation of this phrase in some dialects. "Sware" is a variant of "swear," pronounced /swɛɹ/, with a long "e" sound. "At" is pronounced /æt/, as in "cat." So when pronounced together, "sware at" sounds like /swɛɹ æt/ or "swair-at." This may be heard in certain English dialects, particularly in the southern United States, where "o" sounds are often pronounced as "ah" sounds, as in "y'all" for "you all."
The expression "sware at" is derived from Middle English and Old English.
The word "sware" comes from the Old English word "swǣr", which means "having sworn" or "bound by an oath". It is the past participle form of the verb "swear", which means to make a solemn promise or vow.
The preposition "at", also derived from Old English, denotes the target or direction of an action. In this context, it indicates that someone is directing their swearing or using strong language toward a specific person or object.