This is the Excalibur Guide: https://overframe.gg/build/478247/

This is actually a pretty strong build for a zero-forma [Exalted Blade], it will carry you through the game. Slash deals True damage over time and is good against red health such as the Infested, Grinner, or Corpus Robotics because Slash bypasses armor completely. Basically, Slash will help you finish enemies with yellow health bars faster. Viral is just health damage amplification, it makes any type of health bar disappear 2-3 times more quickly. Grinner and Copus with red Health bars will disappear 3-4 times more quickly with Viral. However, some of the infested in Cambion Drift are immune to Viral, so you are better off using Corrosive against them. So, use [Voltaic Strike] or Shocking Touch for electricity instead of Cold. Corrosive and Slash or Heat is a very effective combination by itself.

• [Condition Overload] is the best damage mod for melee builds. It drops from most of the infested enemies found in the Cambion Drift in Deimos. Against the Infested in Deimos use Corrosive instead and if you want can just leave your blade as Corrosive Slash you can. Corrosive also helps yellow health bars such as the Grinner disappear more quickly.
• You can get Gladiator mods from Plains of Eidolons. Their bonus critical chance only works when you build a combo multiplier aka hit enemies with the blade part, not the beam part. Gladiator Might is a good replacement for Condition Overload if you lack it.
• If you don't find Berserker Fury, Quickening, or Gladiator Vice, then a regular Fury will work fine too.
• You can get Virulent Scourge from killing Corrupted Vor in void missions above level 40.
• [Volcanic Edge] and [Vicious Frost] are 10% Chance Tier 1 Spy Rewards with all 3 Data Vaults hacked. The best locations to farm them are Suise on Mercury, Unda on Venus, Cambria on Earth, Arval on Mars, and Shkolvsky on Phobos.
• This Slash Viral build is for those without [Chromatic Blade]. Use either [Carnis Mandible], [Jagged Edge], or [Buzz Kill] for a higher slash since it is the best damage type to have against armored targets. Carnis Mandible drops inside the level 25-30 Necralisk Bounty in Deimos. The heavy attack kill gimmick can be used to nullify energy drains, burns, etc.
• Disclaimer: For those who are using the Chromatic Blade augment, you should immediately use Molten Impact instead of a Carnis Mandible. Also, match it with a heat-emitting color, if you did it correctly then it should result in Viral + Heat with an emphasis on Heat.
• The rest of the mods you gain by playing the game.

Tip: Go to options, under customize key bindings, and add a mouse button such as mouse 1 or mouse 5 next to your melee attacks. You can also scroll up or down. Personally, I mouse scroll when I want to increase my attack speed, as there is less lag. Once you get it down, it's intuitive and won't smash your keyboard by spamming E.

Note: This build completely smashes the normal Star Chart, and even up to level 150 grinner as it is. However, if you are on Steel Path then use Forma to exchange the normal variants of mods for their primed variants. Once, you have [Chromatic Blade], you'll need to use Heat instead of Slash. Also, once you obtain a 100% status chance with it, it will be time to exchange 60/60 mods for 90 elemental mods.

Enjoy :)