I don't know.  Is this option available for 'cosmic vending machine' rituals? (ie. can my Pure Mortal walk around with a Walker in his back pocket?)

Recommend the second clause of Winter Shield either be extended to one exchange rather than one attack, or stripped entirely.  As it stands, it's less valuable than the mere existence of a defense-invokable aspect

The following is nearly pure conjecture / personal opinion:

The only method I could think of would be to block all access to/from the Nevernever as a whole, since the Ways are not so special that they could be blocked specifically like that, being little more than (comparatively) safe paths within the Nevernever to (relatively) stable and known locations.
That should be able to be accomplished (in theory) by a sufficiently (read: incredibly) large and powerful magical working functionally opposite that of opening a gateway.  Instead of smashing or tearing or otherwise parting the veil between the mortal world and the Nevernever, you strengthen and reinforce it, making it difficult for others to traverse.  This may or may not be easier for communities with more well-defined borders - those borders providing something to anchor to in much the same way as a Threshold.

This will not be absolute, and a sufficiently powerful or determined traveler should be able to break through in time (and maintaining such a barrier would itself be taxing and of questionable value over the long term unless paired with similarly immense defenses of other sorts).

In terms of game mechanics, you'd simply be erecting a Thaumaturgical Block over a large area

Incite Effect would do a reasonable job so long as you weren't too concerned with maintaining the arbitrary mechanical limitations of the source (ie. can't use that Flame Breath shout to set buildings on fire...because buildings can't BE set on fire).

Maneuvers don't have weapon ratings.

Enchanted weapons being used in an attack may either be treated as a mundane weapon, such as a warden sword being used as a very well made sword that is only coincidentally enchanted, or as an enchanted item that is coincidentally shaped like a weapon.  One cannot take the best of both worlds.

Compels are negotiated, and not merely to the extent that they can be refused.  They are also subject to a test of 'reasonableness' to be judged by the table.
Personally, and with the groups I have gamed alongside, 'you lose the fight' is very rarely a 'reasonable' compel.
Something to the effect 'you need to offer a Concession' might very well be acceptable, though.  For instance, an aspect might be invoked representing a dire and urgent need to address matters elsewhere, forcing an opponent to flee, or an aspect representing a fiery temper might be invoked to force a concession in a duel of words (possibly resulting in the beginning of a new physical conflict scene to replace the now-ended social conflict).
This, though, is typically the extreme end of the power of compels.  Handle with care, and remember to negotiate, negotiate, negotiate.  Everyone should come out the other side happy with the results.  If they don't, then something has gone wrong.

What about any spell of the same element, or maybe any specific kind of spell (for example blocks)? This goes for Tedronai as well.

Just about the most lenient I would consider being would be to allow a rote spell that adds duration to a single spell of specific fluff description.
For instance, a spell that erects a convex wall of force.  This could be used as a personal defensive block, or could be extended to protect a group, be put to use as a zone border, or even be represented as a maneuver.  For the purpose of rotes, each of those is a distinct spell.
But it would not extend even to another spell of the same element put to the same purpose, if that spell has a different narrative description (say, a cascade of dazzling lights).

Even this I would only implement on a 'trial basis', and would periodically review with the players, and be prepared to retract or alter.