Mana strike is incredibly predictable (people are basically guaranteed to use it as long as you're in range, especially on whiff cancel when they have nothing else) and you can counter it by simply tech rolling. You can also parry it in certain scenarios. It's basically just a more dangerous Lightning Slash.
Viewing post in Wizard is wildly OP
I think part of what bothers me is how noncommittal it is for such a strong option - unlike Lightning Slice, it's barely punisheable even on parry in most situations. It's such a universally strong move, and any space it doesn't cover, Tome Slap now covers with only 4f startup. Pommel used to at least be a faster jab, but no more - since the update that reduced its startup, they clash.
The zoning character is incredibly good at every range now.