What's the analysis for たりとも? Quoth Edict, means "(not) even; (not) any", and is probably used as such: > (even one question, cannot answer) Is made up of the individual portions ("such things as") and ("even if")? What's the etymology of ? What are some other ways to analyze its construction?

You are close, but yout problem is that you are trying to interpret `...` as a modifying clause. It is rather a subject with a relative clause: 'I could not answer even something that is a (mere) single question'.

But if you are not particularly interested in a deep analysis, you can just understand `` as a fixed expression meaning 'even'.