It’s like falling off a bicycle: you never forget how
(Mukashi totta kinedzuka; “The handle of a mallet that one used to use”)
Abilities and skills gained in one’s youth. By extension, such skills that one has managed to retain even as one ages. In the former sense, one could use the phrase to describe athletic ability that has since faded. In the latter, it’s something like how they say that you never forget how to ride a bicycle.
This one is simply a noun phrase. Our main noun is a compound of 杵 (kine), a mallet – especially the large wooden mallets used in mochitsuki – and 柄 (tsuka), “handle.” The noun is modified by the verb 取る (toru), “to take,” in past tense; the verb in turn is modified by the noun 昔 (mukashi), “past.” Something about the construction makes me suspect that this noun phrase was extracted over time from a longer sentence, but (as discussed below) its actual provenance is unclear.
I haven’t been able to find an origin for this phrase anywhere. Source after source painstakingly explains that the image invoked is of the mochi-pounding mallet one handled in one’s youth (most likely during winter festivals), and how this is a stand-in for skills or abilities acquired and used in the past in general. But nobody seems to know how or when people first began using that particular image for that particular shorthand.
It is considered valid to write 取った as 操った (base form ayatsuru, here in past tense, normally pronounced ayatsutta), “to manipulate (a tool).” My sources do not make it clear whether 操った changes pronunciation to totta in this case.
(“Juunen buri ni karate no renshuu wo mou ichido hajimeyou to omotteru kedo, mukashi totta kinedzuka wo mada ayatsureru ka na.”)
[“I’m thinking of starting karate practice again after a ten-year break, but I wonder if I still have the skills I picked up when I was younger.”]