Well . . . I'm not sure I agree about the r-guitar thing. Two guitars chording forcefully have of course more weight than one, and that may have been exactly what Jerry "felt" was needed. . . . Didn't have to mean that Weir was deficient in any way at that point of the jam, just that Jerry might have wanted more chording weight by doubling the chords.
Weir is a "weird" guitarist. . . he's unconventional. . . but he plays damned fine guitar if you ask me. I love his lines and chords. I love Jerry's too. My one complaint about Weir is I think that Ibanez he played for years and years was not the best sounding guitar for the band. . . . But that's just my personal opinon more than anything. I don't feel its tone and texture blended as well as another might.
Anyway, it doesn't matter as far as I'm concerned. The band evolved and in MY opinion almost every member made great and important contributions through the first five to ten years. (I really don't like Hart's coming back to the band. . . I like him before he left, but rarely feel I want him there after he returned. That's just me and my love of Billy's drummin'!)