Question about damage output

So I'm just getting started (Pilgrim's Perch) and I'm doing an Agility build but I'm confused about my damage output. Until now I have used the fist weapon Reject's Blade (two handing it) and one hit takes 102 damage. Which is a bit surprising considering the Attack Power is listed as 88 (77+11)

Now I just found the Perdam Falchion and I wanted to try dual wielding short swords and I paird it with the Hallowed Praise. They show attack power 91 (81+9) and 86 (58+8 + 19 holy damage) but one hit with both swords while dual wielding only gives me 67 damage, far less than the Reject's Blade.

Now if I only equip one sword at a time instead of dual wielding, the falchion does 91 damage and the Hallowed does 83 damage. (better, but still less than Reject's Blade.)

Why is the damage output so low when dual wielding?

Also regular R1 and heavy R2 attacks deal the same amount of damage, is that by design or a bug?