How would you buff weak perks?

Here's (more than) a few:

Better Than New - Increased bonus to 16/18/20%. Added sabotaging, exit gate opening, and unhooking to affected actions. You now also see the auras of Survivors with the bonus for as long as they have it.

Deception - Can now be triggered by using Active Ability button near a locker instead of replacing the locker enter prompt (basically you can choose when to trigger it, or actually enter the locker to fake out the killer if they know you have it, especially if you also have Head On), and increased the duration of no scratch marks/blood to 5 seconds.

Fast Track - Similar to Deception, you can now activate it by pressing Active Ability button within 2 seconds of hitting a great skill check, so you can save tokens for when you want to use them.

Poised - Increased duration to 12/14/16 seconds, now also provides 5% Haste while active and hides pools of blood + grunts of pain as well.

Potential Energy - Reduced the conversion rate to 1.2% to 1% (instead of 1.5% to 1%, basically means you can charge it faster and lose less efficiency doing so).

Resurgence/Reactive Healing/Solidarity - Instead of granting partial heal progress these perks now temporarily reduce the total charges required to heal (like what a BNP does), which prevents Hemorrhage from hard countering them like it does now. If the number of charges required to heal is reduced to 0, you are fully healed. The effects are only good for that heal and completely reset once you are healed or put into the dying state.

Self-Preservation - Increased the range to 24 meters.

Situational Awareness - Survivor-aura reading when the killer downs a survivor is now always active (was only while repairing a generator).

Spine Chill - Increased action speed boost to 8/9/10%, increased linger time to 2 seconds.

Wake Up - Removed range limits on exit gate switch auras and other Survivors seeing your aura, increased opening speed bonus to 20/25/30%.

Awakened Awareness - Restored the 2-second linger on auras. Starstruck Nurse is gone so it won't be a problem anymore.

Grim Embrace - Added the following: When activated, all Survivors will immediately scream and have their auras revealed for 2 seconds, repeating every 10 seconds until the generator-block duration expires, Killer also gains 5% increased movement speed for the duration. Obsession aura reveal now lasts 10 seconds instead of 6.

Hex: Huntress Lullaby: Now activates on a dull totem upon gaining its first token instead of being able to be cleansed from the start. Decreased maximum tokens to 4. Survivors failing any repair or healing skill check get an additional 1.5/2/2.5% regression penalty per token up to a maximum of 6/8/10%. Reduces delay between skill check warning and skill check by 18% per token (up from 14%) and eliminates the skill check warning at 4 tokens instead of 5. (TL;DR: Can't be cleansed before gaining any tokens, and reaches maximum power sooner than before.)

Hoarder: When a Survivor unlocks a chest or picks up any Survivor Item (not killer-specific items), you get a loud noise notification and see their aura for 8/9/10 seconds. Survivor Items found in chests are more likely to be of lower rarities. (Removed range limit.)

Hysteria - Removed cooldown.

Insidious - Reworked: Reduces your terror radius by 10 meters at the start of the match for 60 seconds. When the exit gates are powered, you become Undetectable for 40/50/60 seconds. (Current Insidious is outdated and never used for anything other than camping, the rework helps you catch a survivor off guard at the start of the match and gives it utility as an endgame perk as well.)

Iron Grasp - Added the following: Increases the speed of picking up and dropping Survivors by 50%.

Oppression - Reduced cooldown to 80/70/60 seconds.

Remember Me - Obsession is no longer immune to the effect. (This not only is a buff but it also makes the perk healthier since it'd no longer encourage fully tunneling the obsession out of the game just to ensure they can't hard counter the perk.)

Septic Touch - No longer terror-radius based, works across the entire map. Now pauses Blindness and Exhausted recovery times while actively healing (like Fearmonger).

Thrilling Tremors - Reduced cooldown to 60/50/40 seconds.

Unnerving Presence - Added the following: Affected skill checks have no great success zone. (Currently the increased skill check chance actually creates more opportunities for great skill checks which can make the perk work against the Killer, so this buff fixes that.)

I disagree with your Head On change though, I think being able to stun the killer for 3 seconds is enough of a hindrance to the killer that you shouldn't be able to quickly chain another exhaustion perk with it, especially since it's the only exhaustion perk that can be used to directly help your teammates. It might be neat if survivors with Head On who were in a locker with the perk ready caused that locker's aura to be revealed to other survivors though, so they know what you're doing and can bait the killer into it.

leader itself is not good. too low numbers. leader should be buffed to 50%. Better than New has a bunch of actions that are meaningless to buff. with current numbers, the perk sounds like it should have window vaulting speed perk and repair bonus perk.

most of dbd perk are bad because they don't want perks to go out of line/be to much game-altering.

out of the perk you named, I thought about buffing oppression to have 0 cooldown but removing random skill-check to be loud noise notification if someone is on generator. All 3 random generators affected by the perk lose 2.5% progression with over-time regression starting.