The problem I have with the whole "why spend resources on this weapon now if I am just going to replace it later" question is that, when taken to the extreme, you end up just using starter equipment until the best weapon becomes available. Upgrading your weapons gives you a better weapon, often with some extra stat boost or status chance. The point is that this makes you stronger, if you can get by without upgrading then great, don't worry about it or just upgrade certain characters as needed. Throughout both games you only get new weapons once per chapter (outside of a few specific points like Zero's final dungeon), so if you upgrade early in the chapter then you will have plenty of time to make use of it before it gets replaced.

Yes, there is. In particular, you want to upgrade Lloyd's weapon in chapter 3 and keep it as a backup weapon even after you got stronger ones in later chapters.

The reason for that is that this particular upgraded weapon gives a bonus to EVA, which is needed to make Lloyd an Evasion Tank, which in turn is needed to beat certain boss fights that you're 'supposed' to lose (in the sense that you can continue the game even if you lose them), but which will give you bonus BP if you do beat them, as well as lots of XP and in some cases a Record/Achievement.

Beyond that, I found that by chapter 3 you get enough U-material that there's little reason not to upgrade everyone's weapons. Also, fights get harder from this point on, particularly if you want to tackle the 'high level monster chests', which is a good idea because the rewards make it easier to beat those 'supposed to lose' fights I mentioned before. So i found it to be worth my while

Also, in chapter 3 you have all the tool you need to efficiently farm Sepith (and thus Mira), so if you're willing to spend a couple of hours doing that, you can upgrade everyone's slots, buy all the Quartz you want, convert enough to Mira to buy the expensive accessories from Imelda (and anything else you need) and have enough Sepith left over to be able to buy the next tier of Quartz when the become available. You can even buy U-material through the Casino, if you feel the need.

I think it pays off if you can afford upgrading early in the chapter. But if you're already close to the current chapter's final boss battle it's probably not worth it.

Also depends on each character and how you use them. If you can't or don't want to spend all your U-materials upgrading everyone's weapons, prioritize physical characters over those that will be typically casting Arts and doing support Crafts.

For anyone who wants to know how to farm Sepith efficiently in this game (and since I accidentally typed up this whole strategy in answer to a completely different question):

On West Crossbell highway, the Black Hunter (flying bug type enemy) drops all 7 types of Sepith. This location is accessible from Chapter 1 onwards, but by Chapter 3, you can have the tools to set up an easy farming method.

You need Noel and Wazy, because their Combo Craft hits lots of times, so if you use it on a Sepith-up turn, you can get loads of Sepith. Give Noel the Sceptre MQ, give both the Septium Vein Quartz, and you can get 50-60 of each type of Sepith per monster this way in each fight.

There are a bunch of ways to make things more convenient:
- Use Lloyd and Randy as other characters in your active team, because Elie and Tio have weaker and/or non-damaging Support Crafts (which you can't control being used).
- De-equip everyone's weapon. give no-one STR or EVA enhancing Quartz and Accessories. Give everyone DEF Quartz. You want STR and EVA as low as possible, because if enemies attack you and miss, you'll retaliate, and you don't want to kill them that way.
- Give everyone Action, Cast and HP Quartz, so you can cast Tear to manipulate the turn-order with. Sepith-up doesn't always show up on the right character, after all.
- You're overleveled enough that the damage from enemy attacks is negligible, but give everyone anti-poison Accessories, since the monsters inflict Poison, which will damage you.
- Give Noel and Wazy the Gladiator Belt and Superior Gladiator Belt, respectively, since it will allow them to regain CP during all the turns you're waiting for Sepith-up to appear.
- Upgrade your Car with all 3 chargers, and park in on the mid-point of West Crossbell Highway (the monsters will be one screen to the right, i.e. in the direction of the city), so you can easily restore your CP if needed.
-If you can't get Sepith-up to land on Noel or Wazy's turn despite manipulating the turn order, use Noel's S-Craft on the Sepityh-up turn. It gives less Sepith (30-40 of each per monster) than the Combo Craft, but it's a lot better than letting all your waiting go to waste.

I think that's about it.

Don't forget to return to the city if you're nearing the max Sepith limits (9999, I think), and spend it all on upgrading Slots, buying Quartz, and converting into Mira for whatever you feel like buying (I'd like at least 2 of each of Imelda's expensive accessories).

Also, I'd keep going until you've gotten everything you want, and still have about 500.000 Mira and 6000 of each kind of Sepith. That should serve you well in later chapters when more expensive things become available.

Good luck! :-)

I can confirm that this is the best way to farm Sepith, much faster than fishing or shining poms.

A few improvements though:
1) Use Lloyd and Elie for your other party members. Lloyd has Burning Heart which has 0 delay (causing him to go again) and can push turn order back one with each use, while Elie has Strike Bell which can advance everyone up. As for damaging support crafts on everyone else, just turn them off in the Status menu.

2) I found it faster and easier to just use the move command to pass turns, issuing that repeatedly is a very simple rhythm that is easier than casting an art. Once you see the sepith-up bonus appear, you can change into turn order manipulation mode.

Originally posted by ForeverZero:

A few improvements though:
1) Use Lloyd and Elie for your other party members. Lloyd has Burning Heart which has 0 delay (causing him to go again) and can push turn order back one with each use, while Elie has Strike Bell which can advance everyone up. As for damaging support crafts on everyone else, just turn them off in the Status menu.

Fair enough. I hadn't considered Elies Strike Bell craft, but doing things this way does mean that Randy can jump in with a support craft that will likely kill all monsters, which is annoying. Elie has at least one non-damaging support craft.

Originally posted by ForeverZero:

2) I found it faster and easier to just use the move command to pass turns, issuing that repeatedly is a very simple rhythm that is easier than casting an art. Once you see the sepith-up bonus appear, you can change into turn order manipulation mode.

I agree 100%; this is how I'd do it as well. Apologies if that wasn't clear.

Originally posted by Dr. Rudolf von Richten:

Fair enough. I hadn't considered Elies Strike Bell craft, but doing things this way does mean that Randy can jump in with a support craft that will likely kill all monsters, which is annoying. Elie has at least one non-damaging support craft.

Originally posted by ForeverZero:

As for damaging support crafts on everyone else, just turn them off in the Status menu.

I guess you missed this part of the post... XD

Originally posted by ForeverZero:

Originally posted by Dr. Rudolf von Richten:

Fair enough. I hadn't considered Elies Strike Bell craft, but doing things this way does mean that Randy can jump in with a support craft that will likely kill all monsters, which is annoying. Elie has at least one non-damaging support craft.

Originally posted by ForeverZero:

As for damaging support crafts on everyone else, just turn them off in the Status menu.

I guess you missed this part of the post... XD

Wait, you can do that???

... I never knew ...

Well, in that case, putting Elie in your active team is indeed the better option. :-)