I had my own idea of a Titan subclass some time ago, where the Titan uses a flaming spear and shield for the super. Grenade button raises the shield to block all incoming frontal damage (including supers), and melee jabs the spear forward (no lunge). Movement speed is reduced slightly, but armour is improved. Perks allow the shield to increase recharge times for the fireteam when damaged, throw the spear for greater range (but with quite a lot of drop, no melee attacks while the spear is airborne), or deflect 50% of damage back to enemies (straight to the sender, if a grenade went off and the shield is up, the thrower takes the damage, doesn't work for supers). Grenades could be a javelin that deals damage on impact and reduces movement speed/knocks enemies back, an AoE incendiary carpet like a Molotov that sticks to walls and floors and hinders health regeneration and movement speed, and the wall-mounted flamethrower from above. Wasn't sure for the melee, your charge up idea sounded good.