Here are some quickie thoughts for the second effect:

Seems like you have two places to make that work: (1) when Ben pulls the saber out before attacking the Knights of Ren, or (2) just before that when Rey and Ben have their mental connection.

(1) The trick with this is you have less footage to work with. For a beat like this it seems like you’d want to focus/zoom in on the saber, but you have about 3/4 of his arc of pulling the saber from behind his back before the shot ends. And without a closer shot of the saber blade, I’m not sure that a flash or bang would work as well as you would like it to.

But I don’t think this idea for this shot is unsalvageable, just that you might need to settle for something a little more subtle. Maybe the saber starts off crackly as Ben pulls it out, but the blade heals/calms over the course of that shot & the following extension of it where Ben does his “OK, you asked for it” shrug.

If I were attempting that, I’d try a simple opacity masking: have the blu-ray footage for those two (or three, if you want to include the quickie interim shot with 3 or 4 frames of blade in it) on one track and lay the identical HAL9000 footage over it. Mask the saber on the HAL9000 footage so that it’s the only thing showing, and then slowly shrink the mask starting from the hilt on out. The tracking should be done for you by using the identical footage.

(2) Same VFX idea as above, but have that effect occur has Rey is holding the saber by her face. The idea being that her connection with Ben is centering/calming her and that’s reflecting in the saber. That might be placing the emphasis more on her than you want, but it has the benefit of enough screentime and screen location to do the effect in a more noticeable & organic manner.