finial

ristikukka The knot or bunch of foliage, or foliated ornament, that forms the upper extremity of a pinnacle in Gothic architecture.
1924, (w), (w), London: Constable & Co., Chapter 24, http://gutenberg.net.au/ebooks06/0608511h.html

Truth uncompromisingly told will always have its ragged edges; hence the conclusion of such a narration is apt to be less finished than an architectural finial.

The steep slate roofs were topped with bronze finials so tall and fanciful they looked like drops of liquid sliding down a thread.