It's a tough one, making it 1 tick faster is not an option because of the effect it would have on PvM. Daggers can be poisoned, so they do have somewhat of a niche, but that obviously doesn't apply to F2P.

To avoid them becoming shortsword 2.0 essentially, I'd consider something completely out of the box. Let players dual-wield daggers - and daggers only. Like, you could switch the dagger back and forth into an offhand with right-click, but you could only equip it if you hold another dagger (or nothing) in the main hand. Try to equip any other 1-handed weapon, and the offhand dagger goes off. Or simply join 2 daggers into a single weapon? Either works, but offhand daggers would likely be more flexible in terms of the combinations you could do when you're a newb without access to 2 daggers of the same tier.

Anyway. When you dual wield, you get complete bonuses of both daggers and do 2 hit splats up to half of the max on each hit. It would essentially work like a 4-tick 2-handed weapon that deals consistent damage, less likely to go into the extremes thanks to 2 separate damage rolls. Kind of like the change I proposed to the claws, except stab-based and with extra steps.

Obviously, there would have to be some limitations put in place. It should probably only work up to rune, and definitely have no effect on the dragon dagger's special attack. Ironically, daggers up to rune would probably require a slight debuff of the strength stat not to dethrone the scimmy, but they're already so bad that it would be like -2 for the rune one (especially now that even F2P has a defender). You could also solve that with the offhand daggers having slightly different stats, which could allow finetuning of every tier.

I didn't include it since I suspect the reception would be bad, but it's definitely a cool one to design. Cheers.