if you are looking to specifically tackle high rank quest then i guess easiest option is to go with High Rank Jaggi gem'ed with Attack Up (as much u can).

although GS is a strong frontal assault weapon do take some time to practise blocking.  you'll be amazed how much closer u stay and get ready for next attack compared to running around always avoiding the monster (or even worse get hit! eg. poison tail swipes)

i am currently using Azure Los set and it was working fine past high rank.  after some armor sphere upgrade seems to be able to withstand some hits even in early G-rank.

but i think in the end, most likely you'll want to make a set that has skills Juju (nyx) listed.  something along the lines of Selene Z...