"lines of light, like framework" I would say that's different, I think that's Spiritual Tension+Adhesion because it matches with the rest of things he's doing in the vision, keeping his part of the vision whole, plus the mechanics matches up with what he did at Taln's temple in Thaylenah. He seems to be using it to prevent injury and as makeshift bracer for better strength & grip
As for the problems with secondary spren theory:
The Nahel Bond is between the Radiant and the high spren; lack of any indication that Shardplates are made of spren; how would one form Shardplate if the requisite secondary spren aren't near, would the Bond(s) be with the same minor spren every time or new ones, how would either work?
I'm not against this theory, mind you but a lot of people are.
Investiture mechanics aside, I think the secondary spren theory is narratively viable. The scenes where Kaladin & Dalinar were surrounded by Windspren & Gloryspren were powerful and both approaching their respective Ideals where they should be able to summon Shardplate (assuming Bondsmiths can or usually do)
I've never been asked to dismantle the problems with secondary spren theory, only what the problems were, but I'll see if I can do it. Let's see...
The high spren itself transforms into Shardblade (or spear or fork) so Shardplate is unlikely to be formed from the body of the high spren.
That doesn't preclude Shardplate from being formed of solid Investiture or indeed, minor spren
We've seen temporary Bonds with Aviar & white sand lichen, it stands to reason that minor spren could do something similar. We already know that minor spren can be Bonded.
A Spiritual Bond might be able to overcome the problem of distance but the thing is that Shardplate being summonable in all situations isn't a prerequisite.