Sword is static based on total stats no troops...but if you're hansel or guild hansel feather is better, or if you're attack build and want more spy stat.
By the way, it's a feather looking thing coated in diamond. "forged by the diamond dwarves", according to it's description.
I'll always call it a feather, it's much faster and easier to type, and everybody knows what you're talking about. Feather is better unless you have high stats and skim, if you fully unload and wait for full regen then feather is better. Swords 10% bonus is based on troop level. If you have 13mil attack stats at full troops and all balanced builds then you have 26 attacks. Each attack you do will reduces the strength of the sword by 500k. So after 6 attacks you have a 10mil bonus. The feather max enchanted is 10mil static attack bonus, meaning it will be 10mil bonus at full troops or 1 troop. Anybody that tells you otherwise doesn't know what they are talking about.
If you have the choice of both, then particularly for hansels and other spy builds, using the abyssal blade for your spy actions, until the feather is stronger in that stat, and using the feather for your attacks, is the best option to maximize the bonuses youre getting. Or, for the lazy ones of us, just do the stronger action with one and switch to the other for your weaker action.
My feather gives me 13,682,560 attack bonus at full troops. It loses 526,252 strength each attack. My feather gives 6.5mil static bonus. If I do half unloads then sword is better for me, since after 13 attacks my bonus is 6,841,284. Hope this helps all the confused people out there.
Depends on build and how u are playing i personally use the diamond sword for the fact that its perm stat bonus as to where the abyssal blades 10% is based off ur troop count as u spend troops the 10% is less effective meaning fighting from pin to using less pots when low troops makes diamond sword more effective in the end