It's mostly in the description of the 1st or 2nd paragraph where you'll notice a difference in how he reacted for one option compared to the other 2. Don't worry though! The update on the 8th/9th will add in items which you can use during the fight to cheese it. And! There's not many things you need to have beat him yet in this build, and one of the things is broken for some reason. It's fixed in the next update along with a lot more things you need to have won to see.
So you'll be able to buy items, cheese it, then enjoy the unlocks soon enough.
I got to admit though, with the amount of people who are having trouble with him. I'm thinking I made the boss fight that's suppose to be hard, actually hard in an interactive fight that gives you leeway to mess up a number of times. Shame I'm adding in a system that will make this and all future boss fights trivial.