PSA: Before you use glass needles to role that perfect Ram, be aware!
I essentially wasted 120 glass needles trying to reroll the Ram Xur is selling to get an INT/DIS role. Over half of the roles I received were pure STR, and the rest were either INT/STR or DIS/STR. [b]Out of 120 roles, I got 0 pure INT roles, 0 pure DIS roles, and 0 INT/DIS roles. [/b]
I [i]highly[/i] suspect this is more than pure RNG - At least for the Ram, it seems that the glass needles are either heavily weighted toward Strength, or are simply incapable of rolling anything that does not have strength in it.
[u]I implore you to not waste your exotic shards on glass needles if you're trying for a Ram with anything but strength[/u]. If you do end up doing it though, reply with your results: maybe I just had the worst RNG ever.
Edit: multiple people have confirmed that the "primary stat" of the Ram is strength, so it will not roll anything without it. Definitely save your exotic shards for something better.