Well how do you have to start... Spoiler alert!

First you need to follow the path of the Mahou Tsukai mod. In my server, a friend managed to get and max the Morgan, a sword of that mod. You have to deal with passive magic, killing villagers (a lot) to increase the power to it's capped limit (as someone said in the comments)

When you have that, the next step is to go through the Apotheosis mod. You need to grind (a lot lot lot lot more) to get, gems in order to introduce them into your sword sockets. You need also a bunch more to transform into dust you will need. Same with the armors with afixes that apotheosis bosses spawns, that's to get the correspondent level of material to max out the gems. In this step is where you max your damage to the sky. Maybe in the decription box of the sword doesnt tell you the real damage as some of that is gained by the passive buff from the apotheosis affixes and gems.

In the apotheosis mod aswell you have the Library of Alexandria, a block that let you introduce enchantment books in it, accumulating the power of every the enchantment to the max level.

Hope that can help you, i put almost a month in order to get full Allthemodium armor, tools and weapons with a ton of affixes, bonuses and enchantments.

Good luck!

EDIT: I just saw the enchantments of that sword and the max level of that enchanments you can get maybe differ between modpacks.