[Klashikari]

Grande conditions are more severe than it looks, so unless you have a very good character setup and equipments, Grande becomes less and less desirable over time.

Again, dual element is not desirable at all. The only point of dual element summons like Oceanos is that you can set them for 2 different teams, and that's about it. Trying to match your character setup for a dual element summon isn't going to be any good except Odin but that's mostly for specific dark team.

As for the last effects like Titan, their effects isn't a "direct" damage boost. Instead, they affect the skills effect of your weapons.
For instance, if you have 10 earth weapons with a skill lvl 10 (total of 150%), having Titan's 80% means that the earth weapons total boost will jump to 270%.