Here's a better post:
https://steemit.com/steemit/@trevorlyman/what-are-your-steemit-slider-settings
So, it seems like once you have 500SP, then you get a slider which allows you to award a percentage of a full vote instead of a full vote. It also allows you to change the vote you awarded :)
@xaero1 Great info. Thanks. I learned a lot. :)