Princess Hunting Dungeon Meister:Experience

Unit experience
Each type of combat unit takes exactly 100 experience points to level up each time. Your units can gain XP by casting spells (including healing), attacking, defending, and killing enemy units. Killing enemy units usually gives much XP compared to attacking but not killing or defending.

Generally speaking, the lower level your unit is compared to the enemy it engages, the more XP it gains. There also appears to be a minimum amount of XP that is guaranteed regardless of how much greater you unit's level is compared to the enemy's.

All healing spells appear to give 10 XP per cast.

Level Up
You will notice that most units get different amount of stats, even when relading a lot. It seems that every unit has different chances to get the same stat that is attainable (for example, Femme cannot get SP or Magic Attack stats because she won't get skills normally to use them).
 * Marwen's Bracelet (Synthesis level S) doubles the chance to get a stat, saving you a looot of time when reloading if you want characters with good stats as soon as possible, but you can only get your first one by synthesis the quickest if it's your first playthrough. The requirements for it:
 * 1 Creator's Drill - Do 06-01 with 100% completion, so this is the latest one
 * 1 Sunora (Synthesis level D) - You can find one at an earlier map or you can synthesize it for 1 Militia Scalestone and 1 Magician's Drill - commonly dropped by Martells (マーテル) and Smoke Spirits (吸魂霊) the earliest
 * 1 Knowledge Scalestone - commonly dropped by Water Maidens the earliest

LevelUp Script
For people like me who reload a lot on each levelup I decided to share my AutoIT script which reloads-reattacks until getting desired stats. Until someone suggests how should I format and post it I will keep it on my talk page. It is a bit long for a comment... Well, you can read about it here - [//eushully.wikia.com/wiki/User_talk:Andy_Scull http://eushully.wikia.com/wiki/User_talk:Andy_Scull]