Film 2/5 watched from the Nikkatsu Noir DVD boxset, the first being 1957's I Am Waiting, which I watched last night. While that one was a pretty decent watch, Rusty Knife was one that I liked quite a bit more.
With its story of two ex-criminals who are trying to move on with their lives - despite being asked to testify for a murder case by the police, and being pressured to say nothing by the gangsters they used to associate with - things are a bit more exciting and engaging. Characters aren't particularly deep but they serve the story well, and the main antagonist for much of the movie is very unlikable (as he should be).
It's paced well and the 90-minute runtime passed by very quickly. I will say though that elements of the ending feel a bit rushed, and there's one contrived event right near the end that feels lazy and a bit laughable. But then that final shot (held for a very long time) is really great, and mostly redeems some of the problems with those last few scenes.