Title says all... how would you change the class without making it omega OP.
Since the community as a whole have a strong hate toward sage, let the community decide...

My take for the whole class:

-Increase the Base DP of the class and provide +1DR per level on the passive. (In the current meta, being a squishy SA trade class means you die before you can output damage). Along with this change, reduce the Base Evasion of the class and remove the +5% accuracy from the passive.

Here is my take for awakening:

-Remove of the overcharge mechanic in Bolt (dash).
-Reduce Bolt (dash) cooldown to 1 second. (this is done so Sage doesnt need to waste skills to get access to movement)

-Bug fixing in general: Spear Bolt not applying core skill if used from mainhand, upsurge damage being inconsistent, arkanom low damage/accuracy since the reboot (all summon classes have experienced weird and low damage from summons), stuttering on Bolt (dash) when hit (lots of classes are affected by this and should be a priority), etc...

-Reduce Divine Executioner cooldown to 6-8 seconds and allow more skills to overcharge it.

-Divine Executioner iframe while going up and SA while travelling (access to an instant iframe with a reasonable cooldown)

-Spear Bolt and Flow: Aftershock change to Super Armor. Remove Stiffness and put it on the Core skill.

-Impaling flash either full iframe while "attacking" or remove the random teleports and let us decide the outcome.

-Increase AOE of rift Storm and Lightning Prison to be on pair with the reboot classes.

My take for succession:

(Succession suffers the most from Squishiness asn lack of iframes)

-Reduce Rift Chain cooldown to 3 seconds or rework the skill as follow: If a skill is pocketed, Rift Chain will have Super Armor. If no skill has been pocketed, Rift Chain will have iframe. This way sage can decide to survive or do damage but not both.

-Increase movement speed while using Rift Chain off CD.

-Increase the cast speed of Void Gateways, spatial collapse and atomagia.

-Remove the gap in Prime: Spea Bolt at the end of the skill. (This is an enormous gap that gets you killed all the time since you cant avoid it or cancel it)

- Change Atomagia so all hits are applied at once instead of one per beam or increase the beam hitbox. (Right now, the usage of atomagia is very limited and used as a CC more than the intended damage dealer).

-Reduce all AP gain from Q block to +10 instead of +20.

-Change realm of anguish as following: Remove bound, frontal guard and damage. Make the skill so it creates a zone where all enemies inside are slowed down.

-Remove the target/terrain check on Ators Mark so you can output the skill normally, specially the 100% bsr version.

I expect to be downvoted and receive tons of negatives but as you can see, all of my suggested changes are just QoL and no damage was added to the class.

Please instead of bringing toxicity, add your feedback and your ideas for the class as the title asks for.

Excuse me but this has nothing to do with the topic of the post, nor the point of having more DR is to resist a grab > combo but to survive chip damage while SA trading.

I understand your frustration with DFS and the more but please respect the topic of this post. 

Sage would return to its own Jail.

Think changing things on the class that doesn't make it more powerful in NW/Siege but more practical in 1v1, which would improve survivability in all situations but not increasing kill count performance in largescale. Mobile Sage has several ideas that are well thought out and a clear indication of what the class "could've been" with more Development time. What makes Sage so good in both kits is it's ability to stump and "artificially" outplay new or inexperienced players by being hard to track with long distant traveling fast or hard to see movement. With this in mind, to make Succ Sage and Awakening Sage more viable in competitive 1v1/DFS/Small Scale, we should look to Mobile for ideas. Here are a few I believe will help both kits, and not make more powerful in NW or Areas/Skill levels it's already strong against. 

I think SA RC should go. It's trash and servers no purpose other then to confuse new players, and kill Sages. ALSO, make Absolute RC quickslotable and Prime RC 15% faster. I don't think another accuracy nerf should be applied either. We're not the hardest hitting class with zero defense and no utility. We only have accuracy. If we were to lose that, we'd hit even less hard in combos especially with artifacts coming out.

Wormhole Dash (Mobile Skill) - 4 sec cd iframe travels Formshift distance but at bolt speed. AA/WW/SS/DD input will do a quick movement providing Succession and Awakening(Would move to MH) a reactable iframe and most importantly, prevents skill pocketing. Wormhole should cancel MH and Awakening/Prime skills. This would have HUGE ramifications for the Succession Kit and also make the Teleport Skills in Awakening not an immediate death sentence.

Absolute Pocket Distortion (Mobile Skill) - Both kits need a more viable and quick CC. 

Absolute Rift Surge (Mobile Skill): 15 sec cd Ator's Mark Damage/CD, Full FG. Knockback -> Bound - Given the increadibly slow speed of 90% of the MH, both Succesion/Awakening should have one Melee ranged protected CC, due to extended animation time, this would prevent abuse in Largescale.

Realm Of Anguish to Purgatory from Mobile - Increase damage and utility of Purgatory, also make it Knockback -> Stun. Maintains -20 DP

Illusion Compression: Function like Summons and slightly increase damage - Allow Sage a means to "protect" himself and play around a temporary summons. Make Quickslottable for both Succession/Awakening

IF Wormhole Dash is added and iframe, Bolt iframe should not be returned however it should no longer require 250 stamina and dps skills to move. Allow it to be used freely, but only 1 additional time after any skill even bolt itself. Therefore you can Bolt -> Bolt, both SA and both costing only 200 Stam.

Upvoted, but I don't know how well we'd fare with the dp gain in exchange for yet another 5% reduction to accuracy because I just do not trust DP on sage, at all, especially with the amount of one-shotting going on. 

At one point in time we had the highest accuracy, one of the bigger aoes and a reliable iframe. Nice niches to have, despite having the smallest, most lopsided kit with the biggest openings and punishability. 

I'm worried it's gonna take more than these changes to make a difference. Because they took sage down in so many different ways, and from so many different angles, most of the improvements we suggest end up being an outright revision of nerfs, which I just don't think will happen.

I do however, hope for the mobile kit.

Mobile kit is key, I think that's how you improve Awakening. I don't think we can essentially ask for more extreme movement utility which the community already hates. So bringing over viable protections and faster CC's along with a better reset would indirectly be a huge buff for awakening. As I've said, Mobile's dodge isn't as cancerous as Riftchain, it's much more practical and fast too. SA Riftchain is a death trap, wormhole is Sorc emulation but not as abusable. That'd give Awakening a reactable iframe, allow for skills to be cancelled and give Awa an extended iframe combo to escape danger. It'd be pretty huge change. 

Whatever happens, I'd just want Realm of Anguish and Reset to be a big part of our plays, the kind of skills to craft an interesting time mage around. 

I would happily sacrifice every other aoe and projectile for a melee to mid battlemage kit if Realm had the dominion and control over space that it deserves, and would be an organic way to express/emphasise his magical ability without being just another aoe one-shot pain in the a**. 

Whether it's a Slow, or a Bleed, or both, whether it deals more damage, or no damage at all, I don't care. As long as it adds value to the kit, has formidable aoe, and actually controls space to turn a zone into a place an opponent actually feels anguished to be in. A slow whilst inside, actually makes sense for him as a time mage, try and capture the feeling players may get from using his 200% BSR, that same wow factor and supremacy.

The rest of the kit can just be swapped out for the mobile kit as far as I'm concerned. Spatial, RC, FT have done nothing but cause hassle for us and the devs clearly can't balance any of them without it being abusable in largescale or diluted to the point of uselessness.

Make RC an 'Bloodborne Old Hunter Bone' style quickstep akin to Awak DK, make Reset like it is on mobile OR turn it into something like Hashashins Hourglass of Defiance, so when activated you can open a rift gateway which lingers for 20 seconds and you can reappear out of if you use your RC quickstep within a certain radius around the gateway. 

There's no doubt so many ideas if they just sat in a room for ten minutes and opened up the conversation. If they'd just admit they backed themselves into a corner with succ sage and wished to try again with a rework I'd respect them for it. 

I think Realm of anguish will never be too good due to the potential it has... In order to make the skill better it should lose the CC and protection, then maybe the skill could do more damage or have better utillity (I still think a 40% slow area with a small DoT should be perfect)