I'm a new player (still about a week from the two-month mark), built around a re-rolled Rudra+Ryu-Oh and Water's carried me so far to Rank 80 as my only reasonably developed element whatsoever so yeah will probably have no choice but to use it. ^_^

For Water I have: 5 SSR Kamihime, a 110% Rudra (pulled a second copy and used an Imperial Chaldea), 4 MLB SL20 SSR event weapons, an SL20 1-star Soul Weapon (Herc's Axe), and a few Level 85 SRs to round out the grid that are near SL20 (should have them all there within the week).

For Wind I have: 0 SSR Kamihime, Houkei x Tenfu as my only SSR Eidolon, no SSR Wind weapons. :S

For other elements I have 1-2 SSR Kamihime, 30-40% Level 100 ATK-boosting event Eidolons that I use for stats and a few Level 40 Gacha Eidolons I don't use since their stats aren't so great.

My past experiences with Lightning were the Tartarus event (which was a busy raid so I just had to get damage in and got all the rewards anyway), and the Yggdrasil GO which at the time I mostly just had to settle for the participation/x battle clearing mission points for (was enough for 1 Orichalcon so I was reasonably happy considering the weakness, without which I was able to clear my first GO Boss against St. Nick this week and get 2 Orichalcons so hopefully will be able to build off that going forward). I don't think I could've done nearly as well in general if I tried supporting multiple elements at once rather than focusing on what is clearly my best one, but yeah events like these where I have a glaring weakness will be the trade-off I reckon. :S