Yes, both guard and phantom weapons can drop from leeching, you don't need to be the host either. It's a very low probability event (around low single digit % chance) but given that you'll probably do many hundreds of these raids, you have a very good chance of seeing a drop eventually. MVP-ing noticeably boosts the chances of a weapon dropping, but still rare.
This is based on a rigorous sample of one and various one-off anecdotes, but the game seems to have a very strong desire sensor - I use only the phantom lance 99% of the time, and I did not get a second phantom lance until all my other phantom weapons were MLB and have foddered many of the excess. Similarly for guardian weapons, the weapon that drops least is the one I want most -.-
Anyway, point is it's all RNG, so set your expectations low so it's easier for the game to exceed expectations
I don't know enough about water to know how practical these builds are there, but both Saraswati and Aphrodite have pretty strong DATA buffs iirc. For light it's pretty easy: 30% DATA from tiara set, another 30%-ish from fluffy, 20%-ish from Mike DA buff and you're at 80%-ish already. Tish TA buff is 50%, so she can easily make a two himes GDATA for 5/6T even without fluffy. Iris and Vishnu both can stack up to fairly ridiculous level of DATA for themselves. The nice thing about GDATA is that I can activate buffs in advance of a FB, so I can for example activate Hagith, then fluffy, then Kaiser without fear of a hime not generating enough BG to burst before the Hagith buff expires.