Trynd should be a slow attacking heavy hitting skirmisher who is practical in team fights

slower moving, slower hitting, a wider array of defensive tools and a bigger sword

When Tryndamere attacks 2.5 times a second it kind of destroys the illusion that the sword he's always dragging behind him is heavy or unwieldy.

And watching Tryndamere split push all day and then scurrying off when some heat is coming his way doesn't feel right. It makes him feel like a bandit who wants to vandalize your benches, lightpoles, trees, public spaces, libraries, your yard and your towers, not a barbarian who wants to be surrounded in violence. Real barbarians in real life were pretty much vandals, but the Barbarian Trope is just a badass dude throws himself in the middle of combat, gets himself surrounded, and then smashes everything.

325 move speed, 0.75 attack speed cap, replace mocking shout with a channeled block ability so he can team fight without being a binary one button champ, and double his sword size and range and make it feel big and unwieldy. Make it so that his auto attack strikes a linear area in front of him and can miss if enemies step out of it-- but if it lands make it smash shit hard. Real hard. Like "I don't give a shit if you stacked armor on alistar ult this shit will fuck you up so get the hell out of the way" hard. Always crits and converts a large % into true damage based on fury or something.

Jhin and Graves proved that ad carries don't necessarily need a ton of attack speed to function, and in a similar way Fiora proved that skirmishers don't really need a ton on attack speed to function-- but their kits have to be engineered with that in mind. I think Tryndamere would be more thematically whole if his sword felt convincingly heavy and he had a kit more focused on surviving in the MIDDLE of the enemy team, rather than surviving while diving and killing one guy then scurrying off, or avoiding everyone and just split pushing all day when that doesn't work. He's supposed to be a Barbarian King, not an assassin.

You could make his ult less practical in 1v1 and more practical in 5v5 or even 5v1. Tryndamere shouldn't be that pragmatic as a dueling champion because of how slow and ponderous he ought to feel-- although he should still be able to make quick work of enemies that don't respect his damage output and don't bother to dodge the sword.

Like, instead of lasting for 5 seconds and having his kit contain a slow and a high uptime dash that lets him basically assassinate people and run away, instead change his kit to remove the "assassination" gameplay and reinforce the "I will fight forever in the middle of combat". Like maybe an ultimate that lasts for 2.5 seconds but doesn't tick down as long as there is an enemy champion within 350 range. That makes it less scary in duels as long as you are running from him during his ult like you should be, especially if his kit is changed to be less sticky; it also makes him extremely scary in large team fights on dragon or baron because he can easily keep at least one enemy nearby and can potentially be immune to death for over 10 seconds.

I realize all this sounds like a terrible idea, but I don't really think it is. What is a terrible idea is just letting Trynd, the Barbarian King, continue to be forced to play the role of That-Assassin-Who-Does-Not-Look-Like-One, the Vandal King.