I'm dumb and didn't take picking up attack powerups in account. I think it's just a set 2 Base Damage per glyph, I believe. I don't know how that adds up but for me it works better for like... Thieves and Rogues, and not great on Monks. I don't know how it adds up on a "neutral" user.
Level 10 Human Vanilla vs Level 10 Orc Vanilla, four glyphs converted, all attack buffs picked up:
Human: 50*1.7 = 85
Orc: 58*1.3 = 75
Level 5 Human Vanilla vs Level 5 Orc Vanilla, four glyphs converted, all attack buffs picked up:
Human: 25*1.7 = 42
Orc: 33*1.3 = 42
Level 1 Human Vanilla vs Level 1 Orc Vanilla, four glyphs converted, all attack buffs picked up:
Human: 5*1.7 = 8
Orc: 13*1.3 = 16
And in general, every time you level up, Humans gain 8.5 damage, and Orcs gain 6.5 damage
So...you need to gain an extra level overall with Orc's early damage to make them worthwhile (and even that won't necessarily make them deal more damage with physical attacks, but there are enough residual benefits from an extra level like more HP, better fireballs, more HP regen, etc, that it's probably worth-it).
Well, that's Vanilla; what about Rogue?
Level 10 Human Rogue vs Level 10 Orc Rogue, four glyphs converted, all attack buffs picked up:
Human: 50*2.2 = 110
Orc: 58*1.8 = 104
Level 7 Human Rogue vs Level 7 Orc Rogue, four glyphs converted, all attack buffs picked up:
Human: 35*2.2 = 77
Orc: 43*1.8 = 77
Level 1 Human Rogue vs Level 1 Orc Rogue, four glyphs converted, all attack buffs picked up:
Human: 5*2.2 = 11
Orc: 13*1.8 = 23
Even with Rogue, unless you get an extra level out of your bonus low-level damage, Human will be better. (Now, if you do get an extra level, then unquestionably Orc is better).
Hm...yeah, I'm really not impressed with a fixed +2 in general. It's probably worth-it if the extra exp slingshotting gains you a whole extra level...probably. But a whole extra level is by no means guaranteed.