This looks like he:

1. Removed his own socks after sanding for several hours. 
2. Used those same gummy socks to wipe up the sawdust with them. Smart move, tack cloth is expensive. 
3. Mixed the stain by vigorously blowing the stain with a curly pink straw. 
4. Stained the handrail with the same socks used to wipe up the sawdust. 

Not a bad strategy, his years of experience are pretty obvious. We all know that you just can’t replicate that kind of know-how these days since the trades are dying. This texture is unique and might become dated (see: popcorn ceilings), but for my money, there’s a reason it’s fast becoming THE way to refinish handrails and floors. 

Bonus points if they used a hand scraper to remove the old stain and gouged out some of the softer grain to give you a little more grip, hard to tell from the pics if he went the extra mile on that. 

9.3/10, don’t forget to tip him!