I'm proud of myself.
I have a fixed 35lb dumbbell that was "the big weight," and since I noticed I was getting more and more reps in before total failure in the rest of my workputs, I thought I'd give that a go for giggles; I surprised myself when I could use that for crossbody hammer curls with relative ease.
Bumping up weights in my body building journey, my ego reps for curling are 41lbs per arm while still being able to hold a lockout.
"The big weight" is now for skull crushers, which I might still need to go heavier on since I can reliably press out 10-12 reps with it.