I can see where putting on some Atk +1000 and Atk +500 can help, but to get really uber, you'll pretty much want 8 Atk/Def 30% on one weapon (probably a Veinslay). With that setup, you get pretty high Atk, and assuming your Defense gets high enough, pretty much nulls most damage.
As for status immunity, there's accessories that do those things, and they're not worth synthing on to a weapon (are there enemies that inflict multiple status ailments at once? haven't seen one yet). And for your spellcasters (Sophia, Adray), synth Int +500 onto a weapon and refine it to +1000. Rinse and repeat (plus there's an accessory you can make that increases Int by 30% when fully refined).
If you want, you can also put status affects on your weapons (only one I'd recommend is freezing, but you can also do that with spells/skills). Also...don't waste synth materials, since unlike the others, they are in limited supply (to an extent...have fun having rare items drop). --- DW Dusk FC: 3823 6430 1741 "Today is the day...the day we bring the end."
Synthing materials aren't hard to come by near the end. Shere 211 first 100 floors have around 20+ or so (haven't gotten them yet), post game dungeons have 5 or so each, I synthd my weapons around 10-12 times, and I still have 16 left. And I know I sold a couple here and there cause I had 20 and didn't wanna leave any chest unopened. That's what, 50+? I ran out of crafting materials refining all my BoPs, but I never ran out of synthing, nor do I think I will.
And can you tell me what item does the Int +500 and maybe where I could get it or 2 of it? No walkthrough I've seen tells you what all the items do. --- Trunks the Weaponmaster
I know, there's a shop in the MoT that sells all the materials except Synth. I just haven't gotten that far yet. I was getting all the Luther trophies I could before I needed to Synth anything else (it's a long way back once I leave and I didn't wanna make it again till I was able to actually get em all). All I have left is the one with the metal pipe and the one w/o armor or accessories and I have all those trophies.
Thanks for the info on the Dark Crystal, I'll have to Synth a few before I hit the MoT prolly tonight. --- Trunks the Weaponmaster