Varus q soft cap?

So today I was doing a dumb build with varus. 6 bf sword items. And uh when I go to q a Vladimir with 100 armor and 300 hp he takes 0 damage. Yes I did hit em. No minions to heal his w was down no face of the mountain no healing support. Everyone in the game was like wtf, lol, get rekt, thanks rito, ect. And my q at that point I believe was doin around 1000 damage.is there like a soft cap for the damage on his q that just broke? I've also noticed that when I hit a squishy high damage ability on a champ they take severely reduced damaged. Ex sion fully charged q on adc does 200 damage when my ad is 250 and you knowsion has like 150% ad scaling on a full q swing. Pls fix this if anything is wrong. Thanks.