I like the Blink and the idea of teleportation in general. I like the idea of having more teleportation-related spells with safety in mind, similar to Blink so I created these spells: Blink Curse and Safety Blink. Now, the names suck, sure, but I'm more interested in feedback on usefulness and balance.

What are your thoughts?

Tactical teleportation is cool. I like how blink curse feels as though you're de-materializing the target.

I think shield is generally more valuable than safety blink. I'm not up on the math, but a +5 to AC is more likely to cause an attack to miss than a saving throw failure via this spell. Also as a note, I don't think you need to worry about projectiles. I think it's a safe assumption that after one round a projectile is done flying (or at least not a threat). For blink curse, I'd be a bit more clear about when the target gets additional saving throws. Generally for spells like that, they get a new saving throw each turn. I think that's implied, but it's unclear.

As a side note, as a player I would be concerned about making an enemy ethereal. It gives the enemy a chance to hide or run without being seen, or even make some hidden attacks if they have access to force damage. I would go for banishment, which surely removes the target from combat, at the cost of concentration. You may want to consider having the targets of these spells be banished rather than ethereal as the primary effect.

Worth noting is that Safety Blink, if it works, can boop something on the first strike of a devastating multiattack and effectively cancel their entire turn.  Imagine booping a Pit Fiend's initial mace strike and watching it disappear for a turn before it can roll its three remaining attacks.  It very much makes sense for Safety Boop to be third-level at the very least given its ability to just outright "Nope" a dangerous critter's entire turn.  Possibly even fourth, though I think that's as high as I'd go and I'm not sure I would.

The spells are interesting indeed, but I share the concern about certain critters being able to fox the caster with abilities that stretch across planes.  Save that I'm not entirely sure it's a concern, really - it almost feels like a feature in that using either of these on the wrong critter could make a situation worse instead of better.  There's not honestly many critters that would apply to, and the ones it would could be used to make for interesting tactical challenges that Master Blinker can't deal with as well.