Boa stomps with ridiculous ease.
Slaver arrow doesn't require the target to lust after Boa, and they have turned inanimate objects to stone such as cannon balls. Her arrows have been calculated moving at hypersonic speeds on account of intercepting multiple cannon balls mid flight.
As for Erza's armors, not a problem. Boa was casually petrifying pacifistas at MF and pacifista are made of a metal that makes steel look like paper. Let me put it this way, a pacifista was able to tank a combined attack from the M3, and by SA Luffy could shred through multiple layers of bedrock (Alabasta), Sanji could deflect blows from Oars and move the giant chain at TB which weight hundreds if not thousands of tons, and Zoro could slice through steel, trains and freaking buildings. The 3 of them combined managed to just push a pacifista back, Boa stopped several during the war.
In general the OP verse is much faster than FT. High and Top tiers are in the triple digit hypersonics.
Here is a great reaction speed feat by Boa
She was able to arm her attack while the shells where still mid flight and intercept them with her arrows. She is way faster than Erza, and Erza can't counter her Hax. Boa petrifies her and kicks her head off.