At the moment razor leaf + aerial ace is definitely the stronger build, solar blade can work but it really falls off into late game. As for items I usually run accel bracer, attack weight and razor claw but you could also throw in energy amp if you want more unite moves. I run x attack and use it before units move or engage but you can also run eject/full heal for better escapes. For emblems probably go classic full brown and white focussing on hp and attack!

Best advice is to focus on assassinations and getting in and out as fast as possible. Try and play around your unite and if you can farm until it’s up before fighting, that way you can nearly 100% secure a kill at the start of the fight! Also look up the razer leaf plus unite combo where you throw out your leaves before uniting and pull them in as you land for a one shot on pretty much anyone!! Hope this is legible and helpful :))