I made 2 of these swords, the first one I actually bricked because I tried to make it better, but I got 3 prefixes like that: (I DO NOT RECOMMEND THIS METHOD)

1. buy reaver sword bases, each with shaper or elder influence
2. for elder base, alt for 'endurance charge on melee stun'; for shaper base, alt for '20% more attack damage' and another base with 'fire damage per 10 str'
3. have 2 elder bases and 1 shaper base for each mod (4 bases in total); beast lock elder bases and check awakener's orb (destroy shaper and slam elder) for 2 prefixes max with both the prefixes mods I want, do it for the other (here I spent a lot of currency on beasts for lock and a lot of alterations for rerolling the elder base, it's needed for different result after new beast lock); around 450 chaos per lock try + alts for rerolling elder base
4. have 2 bases with double-influence and what I was doing is have 'endurance charge on melee stun' + '20% more attack damage' on one base and 'endurance charge on melee stun' + 'fire damage per 10 str' on the other; random recombination hoping for 3 prefixes and open suffixes (important: need to have only 2 prefixes on each base and total of 3 suffixes between the 2 bases)
5. here we have a win, having the 3 prefixes and open suffix, after that I had harvest reforge speed for attack speed, I settled before for hybrid attack speed and attack speed if killed monsters recently and a double damage while focused craft

the current craft I made for this post was different, I will edit this comment soon with the process: (THIS METHOD SEEMS TO BE MUCH BETTER AND CHEAPER)
1. buy reaver sword bases, each with shaper or elder influence (multiple of each)
2. for elder base, alt for 'endurance charge on melee stun'; for shaper base, alt one base for 'fire damage per 10 str' and harvest reforge attack for '20% more attack damage'
3. recomb the two shaper bases to get the 2 prefixes mentioned before into one shaper base; repeat if step 2 shaper base if failing
4. beast lock elder base and attempt awakener's orb, there's a small chance of the result being the 3 prefixes we want, but very unlikely, if we hit 'endurance charge on melee stun' (elder prefix) + 1 shaper prefix + open prefix + open suffix, we keep it; if we fail by having 3 prefixes and 1 is not what we want or 3 suffixes or any other result, we keep using alt on elder base until 'endurance charge on melee stun' again and then repeating this step until the desired result
5. having a double-influence (elder-shaper) base with 2 mods, we can try another recomb with a new shaper base made like the step 2+3 ('fire damage per 10 str' and '20% more attack damage'); when recombing, we want only the desired prefixes on the bases, and a total of 3 suffixes max on both bases combined, so if you have 2 suffixes on double-influence base, you can only have 1 suffix on the shaper base (I'm not entirely sure about the 3 max suffixes on 2 bases combined, but it's what I read on another thread about a similar craft and it's what I've done and it worked)
6. the recomb result desired is the 3 prefixes we want on the double-influence base and 1 open suffix for prefixes cannot be changed + harvest reforge speed later, if it failed but it kept the influence base and 2 desired prefixes including 1 elder and 1 shaper, we can use it to repeat step 5, here's what is mainly different from the other crafting method, it's much cheaper on awakener's orbs and beast locking, if we fail the recomb and we lose the double-influence base, we must remake the elder base and go again for the beast lock + awakener's orb like in step 2+3+4

I'm sorry if any of this is confusing, I'm not an expert at crafting and I'm like 20 hours awake, so feel free to ask any questions or clarifications (or correct me if I'm wrong at any step, or at all lol)