The Superhero Database Classification number, or SHDB Class, is a number that represents the overall 'power' of a character. All traits of a character are used for calculating the Classification.
What it DOESN'T mean
This doesn't mean that a higher class would always beat a lower class character. But the bigger the difference in Class is, the more obvious it is who'll win in a fight.
How is this calculated
( INT^1.3 + (STR*0.5 )^2 + (SPE*0.5)^2 + DUR^1.6 + (POW + (SPS*SPL))^2 + COM^1.8 ) ^ TIER
Super Power Score and Level
Every Super Power has a score (SPS) that is used to calculate the Class. Each Super Power also has 3 levels (SPL). The level is set when connecting that Super Power to a character. The level determines the final score, of the Super Power, being used in the calculation.
His powers mostly come from the crow, so Deathstroke would have to kill it in order to incapacitate him. Unfortunately, I don't think Eric would easily let that happen. He's fast enough toslice a thug without getting shot and jump across rooftops.
Though he may not possess the same combat experience as Slade, Eric can still fight. He put a man's head in a wall, wiped out a gang of thugs without missing even once, and killed a man using a grapple attack.
It's a close call, but I believe with Eric's superior durability and larger arsenal of powers, he'd take Slade out and not break a sweat.