Tryndamere being a melee puts a hard cap on his damage output
Tryndamere being a critical strike melee adc is just not really able to work.
Other champions abuse items like
to ENSURE you don't get away, already having potent catch up and disengage mechanics. This is just puts the nail in the coffin.
But I find myself needing this on Tryndamere just so I can keep up with people. Spinning Strike is his main source of mobility, and you need to be hitting people to get it to a lower cooldown so you can hit people more. Its a paradox. You need it to hit people, but you have to hit people to get it.
The amount of CC in the game is so obnoxious that Tryndamere needs to use his R just to HIT someone, that IF hes not knockbacked/slowed to be useless.
This is why hes forced to be a splitpusher. His blind stat check and 5 second invuln make him a somewhat decent duelist (Not in this meta)
Even in lane its difficult to catch up to people with a conditional mediocre slow....his game is just farm farm farm.
I suggest a total rework:
Passive: Removing crit entirely. Instead, its a fury bar (Tied with his ult) and has a % damage increase the lower his health is. up to 25% at 1hp.
#Q "Sword Slam":
Tryndamere leaps and smashes his target 400 units away. This uses his auto attack timer. Has 2 charges. Critically striking reduces the cooldown of a charge by 50%
This ability would have base damage like Yasuo Q. It can Crit like yasuo Q. The idea here is with 100% crit chance, you can indefinitely keep up with people.
Q crit auto crit gives another Q charge, so no more people walking away from you in fights.
#W "Mocking shout":
Enemies in the area have their damage reduced to all other sources but tryndamere by a flat amount. The amount its decreased for is increased against tryndamere. Probably somewhere around 20%?
This lets him help his team while encouraging tryndamere to be on low health and not play a lifesteal tank.
#E: Undecided.
It will not be spinning slash since Q is now his main mobility.
#R: Unrelenting Force
For 12 seconds, Tryndamere has a fury bar. Each auto attack fills up 5/7.5/10 of the fury bar to a max of 40/50/60. Tryndamere gains Attack Speed and Tenacity equal to the amount of his fury bar.
During this time, if Tryndamere would take lethal damage, he instead prevents it and cannot be reduced below 1 health for 4 seconds.
Tryndamere still keeps his ult, but cant use it early. People needed to activate it preemptively before, so to respond to that the duration has been lowered since its now automatic.
I really like the Ult and Q concepts, making it so he can actually stick to targets and be hard to stop. He still has weaknesses to knockbacks and slows, but they arent quite as hard. He loses his ability to go over walls, but gains much more stickiness to his targets.
Thoughts?

Ranged tryndamere but with mana, your welcome