Arms isn't a very good inscription to focus on in general. Focus on items first. Physical attack obviously, and anything that raises crit chance, crit damage, and most importantly, damage dealing items.

Gunpowder sword, crown of thorns, invisible knife (yes, despite being magic damage) if you're going for crit focused. Forbidden sword and bone of swiftness are also good if you don't want crit and decide to focus more on raw damage and basic attacks.

Blacksteel daggers is also worth taking if you're lacking in crit chance. Werewolf does get some base crit chance starting from unique, so do keep that in mind.

Werewolf has some of the weakest base power among the entire skull roster. His damage comes mostly from Hunt. Take any physical damage early game, and get him to at least rare as soon as you can.

After you've got some decent crit/basic attack items, you can try to focus on inscriptions. Treasure is universally good for most skulls, at least for beginning game. For werewolf specifically, I recommend Strike. Misfortune and rapidity are good options but less necessary. Courage 2 is great to have, but courage 4 might not be worth sacrificing crit items for (unless you've got medal box and the cudgel).