Wow, equivalent weights keep popping up again and again. It is not a nebulous term, the point is you are checking recent webpages. You have to look up chemistry books from 1930 to 60. If corona were not an issue I would have suggested a library trip to read Vogel's Quantitative Chemical Analysis (oldest edition).
Equivalent weight has nothing to do with mol. It predates moles story because the unit originated centuries ago. Mixing mole with equivalents is perhaps the main source of confusion.
Equivalent is the weight of X in grams, that will furnish or combine with 1 gram H or 16 gram O atoms.
Let us take sulfuric acid, ask yourself, what weight (=mass) of sulfuric acid will provide 1 gram H. Note I am not involving any mole concept here. The answer is that if we take 49 g of sulfuric acid we will be able to "generate" 1 g hydrogen atoms.