Experience Loss Is Harsh Bro...

https://poe2db.tw/us/One_Hand_Maces#ModifiersCalc

process split into 3 parts:
* figuring out what tools are available to you
* using that info to guide your choice of bases - whether white, blue, or rare
* following a relatively deterministic path to produce the item you want

generally, essences are split into
* use on a magic item to guarantee 1 rare mod (usually T2-T3 equivalent)
* use on a rare item to remove a mod at (semi) random and add a guaranteed mod

looking at the mod list you can compare the greater essences to their equivalencies. Flat phys is the strongest option imo since it's relatively rare and impacts the final product a lot.

for other prefixes, hybrid and %ed.
looking at the desecrated pool now you can see there's %ed as a kurgal prefix.
so I'd want to find bases with hybrid phys. the DB shows the prefix names, and because we want to start from magic (to essence it) we can also just search the prefix in trade: https://www.pathofexile.com/trade2/search/poe2/Rise%20of%20the%20Abyssal/veZ0RnVZiE on whatever base you want.
Depending on $, availability and whatnot, you can be pickier about the suffixes or the tier of hybrid.

You can also just add the base type to your filter, loot them enmasse, and slap them with perfect transmutes/augs until you get something workable. I put 2os exceptional bases bc I was trying to corrupt into 3os when I did mine.

So you've got a base, or several. Hybrid phys, whatever suffix.
use the greater essence, an omen of Blackblooded, a regular jawbone, and you get guaranteed %ed/-ias.
Now prefixes are done and you've got a solid phys weap. If you have a good suffix, you can try fracturing it here (e.g. T1 str), but otherwise just slam 2 greater exalts (3 ex), and hit it with perfect battle / haste until both stick at once. The "random" removal stays within the affix type that's being added IF the pool is full, which is why you exalt 1st, so you don't remove prefixes with the essence. Similarly, if you bought a rare base and it had idk ele damage or something you were trying to pseudo annul off, you could use the perf Battle on a not-full suffix pool to try and remove a prefix. There's also perfect Abrasion if you were trying to pseudo-annul a prefix off a rare base, bc sometimes you'll find a rare base that has 2x T1 prefixes for cheap bc the rest is bad. If you ruin the base, go again, they're cheap.

You can also, when spamming the expedition vendors, fish for bases that you know you can turn into a usable weapon. If you lowroll %ed, hit it with the perf Abrasion.

https://imgur.com/a/8KA5hT6 like these all cost < 1/3 of a div to make per, except the fractured ones. I kept making them bc it was cheaper to roll new ones than try to fix the ones where I lost the suffix gamba.

You can apply a similar process to rings or boots. So many ppl sell rare boots that are like 5x T1-T2 for pennies bc it doesn't have mov speed. You can get movspd from desecrating prefixes. You can force it onto a prefix with a ~30ex omen, so by buying several bases and just playing the numbers game you can create 30d+ boots by just desecrating them until you get movspd. It's worth using the reroll omen too.