Too much CDR!
There is far too much CDR itemization in the game... Let's remove CDR from:
We can buff them in other ways if/as needed.
Let's rework 
to always give only 10% CDR along with some new non-CDR-related replacement passive.
If marksmen and assassins want CDR, they can go out of their way and make significant sacrifices to build it or bring CDR runes. They can still situationally get CDR from items like: 
Also, 
should only give 10% CDR, but cleaves should stack up to 10 x 3% (from 6 x 4%) for a total maximum of 30% armor reduction. Melee auto-attacks should provide 2 cleave stacks each. This will further discourage marksmen from building BC to replace lost CDR itemization. Marksmen/assassins will still benefit from their juggernaut/fighter allies shredding more enemy armor with BC.
Also, maybe lower 
to 10% CDR and buff its aura to 20% attack speed reduction. It's a cool supportive tank item, but it seems to have become more and more rarely built as CDR has become more prevalent. I think it's too hard to fit 20% CDR on a single item slot into a tank build nowadays. Also, the aura size should be more visible for allies and enemies (perhaps a faint line of particles resembling the aurora borealis or snow flurries on the edge).
Supports, supportive/true tanks, and maybe mages (at full build) should be the only classes reliably capping 40% CDR every game. AP assassins should really have better access to CDR than AD assassins if they choose to build it (
) since they can't fall back on autoattacks to finish a fight. Also, AP sacrifices more to bring CDR glyphs because glyphs are AP's primary rune type.
(or bring some mix of CDR runes).
, who is an AD juggernaut. I don't necessarily want them to be weaker by limiting their CDR itemization. I think the items losing CDR should be given moderate compensation buffs in most cases, which would leave the classes using them balanced around the assumption that they'll not have capped CDR or will be making significant sacrifices by limiting their build in order to obtain CDR.
and 
with the CD overflow mastery is Lucian's next build
) even though other non-tanks, like Ezreal, will sometimes use it. Solo laning tanks are the primary users that the item is designed for, and it happens to fill a lot of the CDR cap. After laning, a top lane tank can also get CDR from supportive tank items 
to name just a few). If 
) or some new actual unique strength to make it stand out.
and transforms into an upgraded version when Awe is fully stacked. Awe grants bonus health. The upgraded version has a stronger, ramping-up aura which can be toggled on, costing mana each second.
, it would provide less AD, and the recipe change would make it somewhat more expensive. Manamune would offer a way for mana-gated AD champions to continue building CDR, while resourceless AD champions would have considerably less access to CDR than before. CDR capping doesn't need to be a super common thing for every champion class, and compensating some items with other strengths, like increased defensive stats, could help improve the game pace.