"Kneeled" Versus "Knelt"
Why do some words have two past-tense forms?
Joshua asked, "Is there *really* no difference between kneeled and knelt? I want to say that knelt is more British, but I can't find anything to back that up. Are there really just two words with the same definition that you can use interchangeably depending on which you think looks or sounds nicer?"
Yes, it appears the two words are interchangeable. A small number of verbs are currently making the transition from irregular verb to regular verb and have two coexisting past-tense forms. Sometimes the distinction is British versus American because the British held on to the irregular form more strongly than we Americans did. The verb dream is one example: dreamt is considered more British and dreamed is considered more American.
Irregular verbs tend to become regular over time. Chide is a verb whose past tense shifted to the regular form relatively recently. The past tense used to be chid, but now it is chided, as you can see in this Google Ngram search result.
Sometimes the distinction between two past-tense forms is a matter of where you live—London or New York—but sometimes the two forms exist simply because a word is transitioning, which seems to be the case with kneel. A Google Ngram search shows that knelt is still more common in both British and American English. Eventually, everyone will probably forget about the irregular form (knelt), and the past tense of kneel will simply become kneeled. Until then, you can use whichever one sounds better to you.