If you go for only Cyberarms and no Cyberlegs you will want to keep a decent AGI, around 3 or 4 to move fast and throw sneaking, the quality Redliner can help too (and it up your arms AGI and STR to 10). The priority becomes A - Resources; B - Skills; C - Attributes; D - Human/Elf; E - Magic.
For Attribute I would go 3 BOD; 3 AGI; 5 REA; 2 STR (with Karma); 3 CHA; 5 INT; 2 LOG; 3 WIL. That's for Human, for Elf it's 4 AGI and 5 CHA.
For the cyberarms max out AGI and STR : Customized Agility 6/7; Customized Strength 6; Enhanced STR+AGI 3. Getting some Armor is also a nice boost, 3 will leave you with 6 Capacity remaining. Though you can get up to 6 more with Bulk Modification. Fit whatever you want in the remaining capacity, a Cyber-Gun can be nice, or if you are going Unarmed, which I recommend since it has non-lethal options, you can get some Spurs and/or Shock Hand. Chrome Flesh has a lot of options, check it out if you have it.
With A - Resources I would recommend to go Wired Reflexes Rating 2 to start out with a really good initiative. It can be paired with Reaction Enhancers to go even higher. Make sure you have Smartlink implanted, either directly in the meat or with Cybereyes (I generally avoid Cybereyes on non-human that start with a boost on their natural eyes). Mnemonic Enhancers is a cool option if you want to have a Bounty Hunter that travel, you add its rating to all knowledge, language and memory test, always nice to help remember faces.