would that it had been more
This is an archaic way of expressing a wish. In modern English, we would ordinarily say, quite simply, "I wish that it had been more." In the passage, the speaker is thanking all of those people he lists for teaching him the spirit of never giving up. He is saying he wishes he had done an even better job of learning that idea from them. (When something 'rubs off on you,' it means that you have acquired a habit from following someone else's example.)
Would that uses a form of the subjunctive mood, or, according to some authorities, the optative mood. (Others insist that English does not have a distinct optative mood.)
A person would use it today to lend an extra flair of poetry or melodrama to something being said. It tends to recall the language used by great poets and playwrights of past centuries.
Pity me, however, I have finished (reading) Ramona. Would that like Shakespeare, it were just published!
^ Emily Dickinson in a letter to a fellow writer, 1884.
It may be that this strange night existence is telling on me, but would that that were all!
^ A character's journal entry in Bram Stoker's Dracula. (circa 1897)
Would that Christmas lasted the whole year through (as it ought), and that the prejudices and passions which deform our better nature, were never called into action among those to whom they should ever be strangers!
^ Charles Dickens, 1835