Remnant Mechanics:
1) I honestly don't understand what these sentences are saying. I've read them like five times and I still don't know what you mean. What line from Psionics, what statblock? I'd like to make the Remnant lists better-organized, but I literally don't understand what your suggestion is.
This line (using
Body Adjustment as an example):
Power Points: Psion/wilder 5, psychic warrior 3
When I read the threads originally, I actually missed that you'd actually already done pretty much everything I'd suggest. The Remnants are listed alphabetically, have a line for per-class RP costs and the class lists are in the thread with the classes. The only real improvement would to be hitting up the more advanced table guides to get them into a sortable table, so that you can organize them by any single value you want (the
Martial Discipline Compendium uses such a table).
2) Looking back at Build, there's a lot I don't like about it. A minute per week of normal time would probably be more appropriate, and the last line about making Craft checks in addition to the effective Craft DC of the Remnants seems... out of place, if not just badly worded. I don't think it's more broken than Fabricate in its current form, but I'd still like to rework it.
Just making the Craft check with a DC bonus based on how many instances are used should be balanceable, as it
does give earlier access to crafting stuff like plate mail, but you still need the money to pay for materials. And mundane crafting has a
tiny, barely mentionable, profit margin (though they do have one by RAW, unlike magic items). Having the DC boost for multiple uses per turn be
mandetory prevents extremely rapid construction because you get confined by one check per interval, meaning it only gets faster when you have the Epic Level Handbook rules in play
and make up for the +10 DC for accelerated construction.
3) I agree that in practice, casting only 1 group of remnants per turn is usually the way to go. It gives you a lot more damage and larger effects on saves, and if you split up your RP, you'll find your effects fizzling out. The main times when you would divide them would be sustaining effects and in non-offensive cases. Putting up a few small walls, healing a bit of damage, and moving over a bit, all in the same turn, can be really useful. They're not meant to be combined more than that except in spellforms (which, as you point out, have their own set of problems).
Keep in mind that damage from Weapon still obeys the remnant damage rules (though now that you've drawn my attention to it, I should add that they explicitly don't add any size modifier to their attack rolls). A CL 7 Remnant Mage can indeed make a cluster of 21 fine greatswords that attack at +7, but if you're up against a pretty standard CR 7 monster with AC 20 and you roll a 10, let's say, you'll be dealing 7d4. So, it's a fairly typical damaging spell for its CL. I should also explicitly say that the weapons don't deal with natural 1s or 20s normally, since a 20 in this case is already 17d4, and I don't want anyone to think that a crit doubles that. So thanks for mentioning falchions - wouldn't have caught that otherwise.
Missed the "same action" clause and that Weapon uses the general rules (you forget to mention that it targets AC with those rules, though), though the situation with building up damage over time (as Weapon has a duration) still holds true.
6) Note that in the introduction, I mention that all remnants must be cast in the same action per turn. That means you specifically can't use a remnant in between every action, only between every turn. As for the examples you gave, none of them seem unbalanced to me. A 1-level dip in Remnant Mage could let you Shift 5 feet every turn. Pretty reasonable for a dip - an extra 5-ft. step every turn seems to me like something a good feat would let you do. As for Shift and Ascend being used to fly... yeah. Remnant casters don't have any other way to fly. They were absolutely intended to be used together like that.
All-day flight for two picks with a level-scaling speed is a pretty good out of combat capacity, and taking away from the speed is a good cost for bursts of high effectiveness.
Spellform idea:
I like your concept (if I'm understanding it right) of a Spellform being a customizable plug-and-play spell-creation system, where you can create any number of slightly different spell effects by swapping out the component remnants. If you can make something like that work well mechanically, I encourage you to post it as homebrew. As is, though, other than some potential balance tweaks with how strict the Remnant component requirements are and how many unique effects are worth a feat, I don't see any way to modify my current system slightly to increase the flexibility. Making a variant partially or completely from scratch seems like the way to go if you want to flesh out your idea.
Hmm... This makes me think of a
slight adjustment, as what I was considering was, itself, an adjustment to the existing setup of a specific, set list of Remnants used in it, differing by use of precasting and scaling parts of the effect, rather than genuinely plug-and-play. This also makes it easier to justify a Feat, as instead of just replicating Call Weapon off the Feat, you'd be able to replicate a wide array of admittedly-simple weapon enhancements in a way that synergises better than normal, meaning you can make a good weapon at a good cost
and pile on upgrades to what you already have. An issue does arise with reams of interactions to be specified, but condensing it into bullet points listing a variety of Remnants, then their similar effects, could get the point across.
For example, the Call Weapon analogous feat could list Acid, Chill, Flare, Sound and Spark together, stating of all of them that they add some amount of damage of their damage type. This means you take five subsets of the effect and turn them into a two-sentence or so description, allowing the feat to cover a lot of ground. This also means
all of the borrowed effects can be listed together, possibly under a genericised heading like Compounds to denote those offer their listed Remnant effect, modified as specified. Such as becoming on-hit effects with the number active reduced to one-third. In the case of a Call Weapon analogue, Enhance and other Remnants that already alter weapons/objects wouldn't need listed interactions because Remnant usage is a Free Action, so you can just use them the instant after your Spellform finishes. The same holds true for other effects, so listing them becomes unnecessary.
Though given the fact they're different in nature and goal, a different name is in order. Spellforms are there to offer higher-level spell effects than Remnant casting would otherwise allow, while the setup I'm considering is there to open up versatility with variable effects that let you adjust the details of the effect as the situation reveals itself. Trading action economy for effectiveness is a common element, and Remnant casting currently has no form of doing so in many cases, drawing on external systems to do so. Being able to expend actions on more complex and, generally, more powerful Remnant effects would make the Remnant "Full Casters" considerably less open-action, as otherwise Remnants being Free Action means they'd Run every round their Con score permits. By giving them useful options that eat Standard actions, they're playing by much more similar dynamics to regular classes. The activation itself being a Swift Action both ties up the Quicken part of the round, for Remnant/Vancian duel casters, and lets the Spellknight still have Full Attack access when they set it off, while the pure Remnant casters have the actions to spend on setting up more mid-combat without impacting direct Remnant use.
If a melee-oriented Spellknight (as they have the effects to go Archery) finds themselves frequently out of range, they can use the same abilities to get or stay
in range more easily or have something better to do with their Standard Action than make a single melee attack. On top of the existing Remnant usage mobility. Which makes them ludicrously hard to actually keep out of attack range, but they're eating quite a lot of actions, and charge rate restrictions (possibly relying on upkeep costs for having prepared being a fraction of the cost to activate) could then cover some of the issues. A longer-range Teleport's upkeep cost would be more RP efficient than Blinks of the same distance, meaning more damage on the next turn than you'd get by using Blink to close the distance.