Guards are pretty whatever for the normal content. There's probably no situation where you absolutely need to have one (vanguards can do as well usually), and if not, then Melantha is perfectly sufficient.
Anyway, for playing for the story the level barely matters in my opinion. ATK/DEF etc. don't actually scale that much. Getting some skills to Level 4 is useful and of course as stuff gets more difficult you sooner or later need some raw firepower, but especially for the first few chapters it's more about understanding what you're doing with your units.
I mean, random example - Amiya has 276 ATK at level 1, 320 at level 20, and 390 all the way at level 50 (all before promoting of course). It's not insignificant but it's rarely a decisive difference. This is not like an RPG where a Level 20 character is roughly 20 times stronger than a level 1 character; it just scales stuff a little.
last edited at Sep 7, 2020 3:00PM