That's because Your readout is from ATMA (which displays damage from ethereal .07 weapons correctly) and Tubba's readout is from GoMule. In-game Tubba's weapons shows a different damage.
Edit.
Here's an example:
GoMule readout
Code:
Death
Colossus Blade
HelElVexOrtGul
One Hand Damage: 194 - 509
Two Hand Damage: 456 - 903
Durability: 26 of 26
Required Level: 63
Required Strength: 144
Required Dexterity: 80
Fingerprint: 0x137ff884
Item Level: 87
Version: Expansion
100% Chance to cast level 44 Chain Lightning when you Die
25% Chance to cast level 18 Glacial Spike on attack
Indestructible
425% Enhanced Damage
20% Bonus to Attack Rating
+50 to Attack Rating
Adds 1 - 50 Lightning Damage
7% Mana stolen per hit
50% Chance of Crushing Blow
17% Deadly Strike (Based on Character Level)
+1 to Light Radius
Level 22 Blood Golem (15/15 Charges)
Requirements -20% Ethereal
5 Sockets (5 used)
ATMA readout.
Code:
Death
Colossus Blade
'HelElVexOrtGul'
One-Hand Damage: 175 to 509
Two-Hand Damage: 413 to 903
Required Dexterity: 78
Required Strength: 141
Required Level: 63
Sword Class - Normal Attack Speed
Indestructible
Item Version: Expansion
Item Level: 87
Fingerprint: 0x137ff884
+375% Enhanced Damage
+50 to Attack Rating
Adds 1-50 lightning damage
7% Mana stolen per hit
+1 to Light Radius
Requirements -20%
20% Bonus to Attack Rating
50% Chance of Crushing Blow
Indestructible
25% Chance to cast Level 18 Glacial Spike on attack
100% Chance to cast Level 44 Chain Lightning When You Die
Level 22 Blood Golem (15/15 Charges)
17% Deadly Strike (Based on Character Level)
Ethereal (Cannot be Repaired), Socketed (5: 5 used)
In-Game screenshot.
Another edit.
Actually Tubba's readout should probably say 300% ed instead of 250%... I don't know why it doesn't. Maybe it's a difference between Oath and Death, though I can't really see why there should be any.