No it is -24 damage a second.
I have no idea how you got -45.
(HKQ impacts base damage, which means the doubling of attack by Col smash and the -20% attack penalty of twin blades apply to it. Although even without that it would be -30 DPS, not -45).
Anyhow:
Old level 10: 88 base damage + 60 HKQ + 62 Heroic Strike = 210
New level 10: 88 based damage +48 HKQ + 62 Heroic Strike = 198
Or a ~5.5% damage reduction.
At level 20:
Old: 91 heroic strike, 130 base attack, 60 HKQ= 281 damage per attack
New: 91+130+48 = 269 damage per attack
~4.5% less damage.
Given Varian’s winrate is in a fine spot, and this was his strongest talent level 1… this seemingly makes him slightly under performing.
Except it also buffed some talents—which will probably make up some of that gap.
So yeah, I don’t see the issue.
It’s a pretty small difference unless you decide to ignore his trait.
If anything this impacts Colossus Smash more, as it only get about 35 damage per attack from trait.
Going from:
280+150+34 (464)
To 434, or a 7.5% decrease at level 20.
190+150+23 = 363
To now 333, or a ~8% decrease.
Add in that 30 damage becomes an extra 7.5 damage when you apply the Col Smash rebuff…
Yeah, it hurts Col Smash (and taunt, although I don’t think taunt varian worries about that damage nearly as much) worse than twin blades.