And 5 trusts which for me would be Sylvie Ygnas Monbereaux Qultada and Ulmia/Cornelia. Which all give buffs?
Ygnas offers no buffs relevant to a scythe WS damage, Sylvie offers the attack bonus of a GEO who hasn't bought a Dunna yet, Monbreaux offers at best +10 to all stats, Qultada offers a very weak chaos roll (if you're lucky), and Ulmia cannot cast Minuet unless you're also using Joachim.
The guy in the video has 7200 attack, you will likely have about 3k with the trusts you listed. Maybe 3500 if your personal buffs are up.
Edit: I was wrong, Ygnas could do an attack bonus if he chooses to use the right TP move, and it lasts 60 seconds so...IDK...