Whetstone

For what I'm going for with this list, I think it is. Whetstone has some advantages if you're going more all-in on relic weapons, which this deck is trying to do (10 relic weapons, only 1 Icaria in the market). Whetstone buffs any relic weapons you drew before you found an Artisan, which happens fairly often. 5 attack Runehammers are a lot better than 4. Same for Daisho (the real reason to run Whetstone). Even Sword of Icaria appreciates a buff. You don't get blown out by a single Stand Together and if you get enough buffs between Whetstone and Artisan, even Finest Hour won't blow you out. Having effectively 7 Artisans is a lot better when you're running 10+ weapons. Also has synergy with Smuggler's Stash (the weapons get buffed by Whetstone twice) and helps you get lethal at least one turn earlier, sometimes more with Daisho.

I'll actually be uploading my tournament games with this deck on Monday. There were multiple situations where Whetstone was big.