Using Exalted on crafted items

Question about this.

I purchased a six link sword and crafted up to decent damage rare.
I added a damage prefix with the bench.
There is still room for more affixes.
If use an Exalted on this, will it overwrite the crafted mod, or add to what I have now?

Exalted orb only adds a mod, never overwrites one. Set the advanced tooltip option in your settings and hold the ALT key when you hover over an item. It will show what mods are on an item. A rare item can have 3 prefixes and 3 suffixes. So if you count less than that, an exalt will add a mod. Exalts are pretty valuable though, so make sure you want to give up the currency for a chance at a mod you want. You may end up making the item less valuable.

In case of your Lion Sword, it would be a gamble. The weapon can not be effectively multi-moded and you already spent exalt to get one mod on it.

I would say it is rarely worth using Exalted Orb on an item unless it is already very expensive item on its own and only way to add more mods is to slam it--use Exalted orb on it.

Vorici in Research lab can be used to provide effect similar to using Exalted orb on an item. This is often "cheaper" than just using Exalted orb.

You should also be sure you can not brick the item you are slamming. Certain mods can actually make the item less valuable or outright broken--imagine you slam elemental or chaos conversion mod on a weapon intended to use with pure physical cyclone setup=brick.

I definitely do not want to brick.

I guess I'll just grind delve and syndicate.

Thank you

If this is for the character Glass_Prison, it's definitely not worth it. You should only ever exalt an item if you can't get straight up buy an upgrade for less than 1ex. In your case I think you've heavily overvalued having a second 6 link - there's no need, you'd be much better off having a higher pDPS weapon with a 4 link. Even Starforge is only 2-3 ex at this point in the league. Also, there's a ton of other items slots you need to address first in which you can find easy upgrades for way less than an exalt. Your belt doesn't even have life on it for example - pretty sure you could find a big upgrade for under 10c.