Ok so really enjoying Bloodstained, but am surprised my switch does have fps drop during certain times. So far my largest gripe with the game is the limited information your shards do (e.g. mostly with familars, like how much damage they do or other abilities they get as you level/rank them up).
OH, well you are a couple years behind and theres loads of FAQ's but I will summarize.
MOST damaging shards get more powerful as you farm more shards. Thats the Grade.
Rank is increased by upgrading and requires crafting materials. The description says what the Rank does but normally it covers a larger area or hits faster.
Some shards gain nothing from Grade, some gain nothing from Rank, some get nothing from either (Utility and movement shards).
Protection shards get a slight increase in power from Grade, and from Rank usually get the ability to occasionally nullify a type of attack.
Familiars just keep doing more and more damage, with Rank, Grade, and Level.
The book familiar also gives you more stat boosts with each Rank.
The chair restores MP. Increasing Rank only gives you more varieties of chairs, which is useless but fun.
Increasing Grade slightly boosts the MP restoration, but not by much.
Detective Eye gets nothing special until Rank 9, where it auto collects items, and thats actually useful.
Boosting shards get slightly more boost with each Grade, and the Rank is in the description.
Augment Gold gets you slightly more gold with each Grade, and Rank increases the probability of a super bonus drop.
Alchemic Bounty gets you more items with Grade, and increases the likelihood of it happening at all with Rank.