Shoot, Treat somehow got left with that default 20% Variance. That's gonna be another patch later, but for now it's not a HUGE deal.
Star Burst has a lot of weird interactions- it also can't be dodged by most evasion effects! I'm not sure if I ever mentioned this properly, though.
The second Block symbol is the speed boost from your Hasty Hat; I gave all the "On-Block" effects a Block symbol and never really changed them. In the future, I could probably make a special symbol for each one (by which I mean a tiny icon crammed in the corner of a Block icon).
I really should get rid of Optimize. It's a holdover from RPG Maker's defaults, but Ruphand was not designed for it at all as a lot of the gear options at any given moment will be sidegrades rather than upgrades. That'll probably be in the next bugfix patch too. (Clear, of course, can stay.)
Any monster that's "permanently missable"- usually a boss lackey that you're not 100% guaranteed to fight, like the aforementioned Gem Servants- will be automatically added to the Bestiary.
The thing with Guard Down is that it's Instant- it takes only a single tick. If the Black Knight's starting Iron Ball +'s 65% windup, you could quickly Guard Down, throw a Super Pepperflask (or even an elemental Formula if you have Haste items), then duck back behind your shield. Every Drive also raises your Starforce cap by 25, so you can now throw out a bigger Star Burst.