So Sajan has this ability to roll dex instead of str when punching. Another is he can use as many blessings and recharge them instead of discarding them.
Can he punch the monster using dex and use as many blessings to multiply the dice rolls he can do?
If not, then what are the uses of the power he has with regards to recharging blessings?
Absolutely. He can activate each power 1 time during a check. But there is no limit on how many different powers he can activate. So activating both is fine.
Remember that each player may not play more than 1 card of each type or activate any 1 power more than once during each check.
He can also use his power for lots of blessings when he attempts a combat check even with out his unarmed combat power. So if he has a dexterity based weapons and lots of blessings, look out. That is part of what makes Zen Archer role so deadly. But giving him a weapon card feat in general can be helpful for either role. It means he can reveal that weapon and free up an item slot that Amulet of Mighty Fists was taking up.
Yeah! Give Sajan a few Weapon card feats, WEAP prof, a Deathbane LCB+1, and maybe Shock Longbow, and lookout. He'll be able to kick butt on his own turns, and help out allies on theirs! And he doesn't have to worry about discarding his weapon because he can still fall back on his fists for a d10, minimally.
I took my Sajan Zen Archer route like this and haven't looked back.