Yup, that's her trustworthy combat knife. At first she didn't mean to use it so often, but energy cells for her plasma defender are hard to find, so she uses knife to save ammunition. But with time she got in love with it.
Another duel took place in the Wild West and another Fiend had died. This time
Blondie faced an extremely dark-skinned girl called
Violet. Violet was surrounded by many feral dogs so Blondie
sneaked to her hideout, but Violet's dogs alerted their owner of an intruder, and so
the duel was at hand. It lasted much shorter than the one with Nephi, Violet wasn't as strong and she relied on
a hunting rifle instead of a melee weapon. A few well placed swings were all that was needed
to end Violet's life. Her puppies attacked afterwards but Blondie dealt with them too. After the fight was over, she
posed on Violet's corpse, until someone took a pic of her. Looks like it's her habit to pose on her dead enemies on occasion. Afterwards she headed back to McCarran,
meeting an NCR patrol on the way.