I've started a tactician mode playthrough recently and things were going pretty well up until I faced bosses like Redeaka and had to protect Malady on the Lady Vengeance. I held my own, but keeping my characters alive is a constant worry. Should I invest more points into constitution? Most of my party is just shy of three hundred HP range and I'm level Nine after escaping to the Hall of Echoes.
I had this same question at first. I would tend to suggest, instead of investing in constitution, putting those points into other attributes. There are other ways to protect your characters when they’re in trouble — potions, for example.