I recently changed guilds and had to wait some time before being able to buy from the Guild Shop. I accumulated some Merits during that timeframe and opened up 15 Gladius Cases at once.
Luckily, I got some boost for my GF account. I can't remember having 5 GF Gladiators in one opening. Three of them are Katrelba Gobson and I was able to level her up. "Only" 1 HP more, but this might decide battles once in a while ;-)