True that. As far as sanctuary cooldown, the visual effect is you not taking any DMG for 1 second but it used to be 2 seconds which was when it was very good, which was why it got nerfed to 1 second. Not totally useless though but easier to die.
An offhand mythic extra would be nice though. I know we have engima, vanish and Nova but most of them don't get used for most builds . Vanish used to be often used but when stealth nerfed, it's not gonna be used anymore and even more so due to internal CD changes with procs so you're better off with the actual skill ability.
Although, vanish still has its uses somewhere but it's the % chances that are low and the duration of stealth and the internal CD being the same as the actual CD of stealth , a long time.
Enigma is useful but mainly better with an A.I since it's unpredictable where it goes sometimes. Nova works but the sky isn't high enough tbh but it helps with elemental Crits when you need it in frozen build but that's it really. Not many uses.
I know not every build needs an offhand mythic but maybe one more could help. I'm not sure what it could do though but it could deal a high amount of DMG for offhand to probably help with variety of build creating and more controllable in some form but it would be a game changer in arena and PvE.