There are a lot of English words ending in -ce. In most cases (think convince, advance, lenience) they just come from Latin, but a small minority come from Old English and Proto-Germanic. Pretty much all of these Germanic words used to end in an s, but the spelling was changed to preserve the breathy sound of the sibilant. One well known example is the plural of die being dice, although it was originally dys. Here are some others:
Hello! I'm Adam Aleksic, a sophomore studying linguistics and government at Harvard University, where I founded the Harvard Undergraduate Linguistics Society. I also have disturbing interests in politics, vexillology, geography, board games, conlanging, and law.