Betty Ross's sword is pretty mediocre sadly. Your hero needs to have a ridiculously bad slot 1 for it to be any good.
Compare it to the Darkhold which gives more than DOUBLE the damage (to mental instead of physical) and brutal stirke rating/damage (albeit, that's pretty bad).
Depending on your roll to boss damage, each 1% is the equivalent to 40 damage rating. The one I rolled has 2% but I believe it goes up to 5%?
The vulnerability proc has a low chance and doesn't stack with existing vulnerability procs, just overwrites. So again, unless your hero of choice has only poor methods of applying vulnerability, this ends up being pointless.
The Dragonfang sword blows Betty Ross out of the water. +1 Fighting translates to +400 damage rating (provided your skills actually have the "Fighting" tag, and you aren't already at rank 7). The Crit and Crit Damage can roll pretty damn high for a slot 1 which makes it Best in Slot for a lot of heroes/builds. The proc's are largely mediocre (due to cooldown/proc chance) but yeah... still way ahead of Betty Ross for any hero I can think of that would use either.
I currently use Dragonfang for Thing but it's a good option for Thor, Deadpool, and Hawkeye too. I've got 2 and will probably use equip one to Hawkeye too.
Betty Ross I've got sitting in my stash with no good options sadly. Haven't found a hero to equip it on yet