Most things in the game take meter off the Arcana Gauge (Bottom bar). Homing Cancels, Guard Cancels, Supers, Arcana Supers and Critical Hearts all use this gauge. Of course, how much it takes off varies with what you're doing...most take one bar though. Everything else will mostly come off your force gauge, the circular meter by your character portrait (Extend Force, Arcana Burst and Arcana Blazes are used by the force gauge).
You start each match with 100% Force Gauge, but it does not recharge in-between rounds. Doing any of the previously mentioned actions with your force gauge meter drains it to ZERO. It will slowly recharge (Recharge rate dependent on the action used). Bar will turn blue once it is ready again, red indicates down time. The rate at which this bar recharges is also effected by your Arcana.
As for Arcana Gauge you start off with one bar, and you can gain a maximum of three. When you hit the enemy, have them block you (Or have the reverse done to you for either), your maximum usable gauge increases by one bar. When you use your Arcana Gauge, even after it has increased, it will not reduce but turn red. After a set period of time, it will recover back to its maximum. While your gauge is red, you cannot increase your maximum until it has recovered. This meter DOES refill to your current maximum inbetween rounds.
Basically, your meter doesn't increase limit until you've been fighting for awhile. Thus spamming meter at the start of a match can be problematic in the long term if your opponent sits on their meter. (You having one bar...them having three)
Guts is a health threshold effect, different for each character. Basically they kick in to prevent you from being killed as fast. Imagine it as a slight zone of HP where you get an adrenaline rush before you die.