Great greatsword damage difficulties

After a few days of getting used to GS I’m in iceborne now and just beat shrieking Legiana, but my hunt times have been worse than I could have ever expected (shrieking without the other Legiana took me 26 minutes and I captured!?!). Although I’m pretty sure half of it is from my underuse of the clutch claw and wall bangs, I’ve been losing it with the combos. I’m really confused on why I keep accidentally triggering a small sword hit that disrupts my combo right after my first strike when I try to charge the next strike. It seems to trigger more often than not but sometimes the combo works normally.
Second issue, is there any point in elements with this weapon? With my previous main, insect glaive, I kept updating my weapon for better damage or a more suitable element, but there doesn’t seem to be much of a point. The base attack on all my accessible alternative weapons doesn’t really change and so I’m still using the final defender greatsword, is there any point to me picking and choosing elements when blast is so reliable and the base damage doesn’t change?
And finally, I’d appreciate any tips for my dps or like tips for general improvement and good monsters to practice specific combos on (I still can’t tackle coherently)