Can I win with an additional point coming from conquering with Trinity Force and Skyfall, if this is the first battlefield conquered and I'm on 6 points?

Yes, you can win the game in this scenario.

According to the RiftJudge FAQ regarding this exact interaction (FAQ 8622), when you are at 6 points and conquer a battlefield with a unit equipped with both Trinity Force and Skyfall of Areion, you will reach 8 points and win the game.

How it works:

1. Conquer Action: You successfully conquer the battlefield. Because you are below 7 points, you gain 1 point from the conquer action itself (6 → 7 points).
2. Triggered Ability: Skyfall of Areion causes the "Hold" effect of Trinity Force to also function as a "Conquer" effect. Therefore, the Trinity Force ability triggers off your conquer action.
3. Chain Resolution: The triggered ability is placed on the chain. Players may respond with reactions. Once the chain resolves, you gain 1 additional point from the Trinity Force effect (7 → 8 points).
4. Victory: Upon reaching 8 points, you win the game.

Important Nuances:

• Bypassing Restrictions: The requirement to score both battlefields in a single turn to reach the final point only applies to the game action of conquering itself. Points gained from triggered abilities—like the one from Trinity Force—bypass this restriction and allow you to win the game even if you have only conquered one battlefield.
• Sequence: The point from the conquer action is gained immediately as a game action, while the point from the Trinity Force trigger is gained when the ability resolves from the chain.