Black lesion on cattleya leaf

[Grim Tuesday]

About two weeks ago, I noticed this black lesion on the leaf of a previously thriving cattleya warcewski seedling. I sprayed it with a fungicide, separated it from my other plants, and transferred it into a less retentive media (it had previously been in "precision" orchiata and though the roots seemed happy, it was not drying out ever). Today I peeled the sheath of the pseudobulb and saw the lesion has not gotten to the rhizome. I don't think it has been growing since two weeks ago. So here are the questions:

1. What is this?
2. Should I cut off the majorly affected leaf? Or just leave it as is? You can see other leaves also have smaller black lesions on them. I am leaning towards doing nothing and letting the new growth develop.