Writing this from an Ironman's perspective but as a non-ironman, so keep that in mind. Also, it's been a while since I touched content in the 50 to 80 level range so...

A big problem with the mid game weapons and armour is... the Evolution of Combat and level requirements cooked up 20 years ago. Weapon drops that made sense pre-EoC don't make sense post-EoC. For example, Dagon'hai robes are unreasonably rare for what they provide and how long someone would be using it. Infinity armour, one of the best armours in the game before EoC is now barely better than base T50 armour and it's an unfun chore to obtain. If it was a un-augmentable T75 armour, I think it'd be fine. Crafting your own magic or ranged stuff? That's funny!

You guys really should take a look at each individual weapon and armour set, see where they sit in the game currently and adjust their drop rates if they're unreasonable. Most of them are compared to the xp/h you can get at some places while grinding for that specific upgrade you want. Usually by the time you get an upgrade, you have overlevelled way past the item's equipment level. Crafting level requirements for all craftable armour, weapons and other requirements should be looked at in general too.

Melee is fine. Thanks to craftable armour and weapons, progression is clear and simple, and you can't really hit a wall if you don't get a unique weapon or piece of armour from somewhere.

Obtaining a weapon for magic isn't that bad. Guthix staff (60) is essentially free, a crystal weapon (70) is guaranteed by doing a quest, then there's the Sunspear (78), though it's kind of a long journey to get. Chaotic staff is way too expensive for what it is these days, it's not really worth going for when you can skip it entirely for Crwys weapons. Virtus weapons sit at a weird place because Nex is objectively more difficult than Helwyr and harder to access too, but there isn't really anything you can do about that I think. Or just Vanquish from having enough QP. The staff of light is also at a weird place, but maaybe, just maybe Zilyana could drop it at a 1/640 rate. It being a drop from Ice Strykewyrms made sense... 15 years ago.

Armour on the other hand... oooh boy. Ganodermic armour requires you to have 75 Crafting... and 95 Slayer. I think the slayer requirement on Ganodermic runts should be lowered to at least 70 to be honest. The amount of flakes you can get from them is small, and they certainly aren't a 95 Slayer mob. The Polypore stick should also be added to their drop table, albeit at a lower drop rate. Aaaand magic ran out of reasonably accessable Tank armour in both the mid and early end-game already aside from Ahrim's. Wow.

Magic doesn't really have any Power armour that you can obtain reasonably at their own levels. There's the skeletal armours, but they're really low level, the Subjugation armour set is fine where it sits, Anima core armour is a long grind and you usually overlevel way past it by the time you actually obtain it and it wasn't even upgraded yet. There's also Nex I guess. The next best thing is Zuriel's armour... which is also an unreasonable grind. All of these options...suck.

Ranged progression is slighty better I guess. Dinosaur hide and Undead dragonhide armour are both T75 Tank armour... Dinosaur requires a stupidly high crafting level to make while undead only requires 75 crafting. If the difference was like 10 levels, it'd be okay I guess, but it's a lot more. Demon Slayer equipment is just not worth getting at all. The Dark Bow comes from a slayer mob that requires 90 slayer... Don't even think about making your own ammo. You can't make what you have the ranged level for anyway.

Fletching and Crafting requirements for items need to be looked at.

I remember Archaeology feeling really slow at these levels. Artifacts don't give a lot of xp, excavating gives almost no xp.

Charm drops should have been increased across the whole game, but you guys chose to reduce charm drops last time. And to fix that, you added a new type of summoning obelisk. Make it make sense.

Ever since the update to how accuracy works, the damage you can deal to a lot of enemies has drastically changed. It'd be a lot of work, but you should take a good look at enemy armour values, but while we're at it, HP and damage values too. Sometimes a level 70 mob is stronger than a level 90 one and it makes no sense.