Feisty is one of those words that we all know. It's used a lot in ordinary speech, and generally, with a positive implication. Here's the usual definition:

1. Touchy; quarrelsome.

2. Full of spirit or pluck; frisky or spunky.

The etymology though, is down right odd. Feisty is from feist.
Feist, a word you'll sometimes still see used in the south in the old form fice or more commonly, fist, in reference to a kind of dog. A "fisting dog" is a small, nervous, even belligerent little dog. Over time, the word feist, in the adjective form feisty, has evolved from describing a canine personality trait to describing a human personality trait. I hesitate to point out that feist, like fice, is derived from Middle English fisting, which means "a blowing, breaking wind," derived from Old English fisting, itself derived from the Proto Indo-Europen root *pezd-, which makes it cognate with Latin petard.

Petard, which most of us probably think of in the context of Shakespeare's reference to being "To be hoist by one's own petard," refers to a variety of small explosive devices. In Hamlet when the hero says:

For 'tis the sport to have the engineer
Hoist with his own petard, an't shall go hard

But I will delve one yard below their mines

And blow them at the moon.

Hamlet III.iv ll. 202–09

Shakespeare, or rather Hamlet's, reference refers to someone being blown up by their own bomb, either figuratively or literally. The standard definition of petard is

1. A small bell-shaped bomb used to breach a gate or wall.

2. A loud firecracker.

The first use of the French loan word petard in English according to the OED was c. 1598; Shakespeare's use was in c. 1604, when it was still a fairly "new" word borrowed from French. The French word pétard was used to refer to an explosive gas bomb typically used in war to destroy city gates and walls. French pét, the ancestor of French pétard means "fart," and was derived from Latin peditum, which, yes, you guessed it, derives from the Proto Indo-European root *pezd-, just like English feisty.